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FLYING  MACHINES: 

CONSTRUCTION  and  OPERATION 


A  Practical  Book  Which  Shows,  in  Illustra- 
tions, Working  Plans  and  Text,  How 
to   Build   and   Navigate    the 
Modern   Airship. 

By 
W.  J.  Jif\CKMAN,   M.  E., 

Author  of  "  A   B  C>tof  the  Motorcycle," 
"Facts  for  Motorists,"  etc.,  etc. 

AND 

THOS.  H.  RUSSELL,  A.  M.,  M.  E. 

Charter  Member  of  the  Aero  Club  of  Illinois,  Author  of 
"History  of  the  Automobile."  "Motor  Boats:  Construc- 
tion and  Operation,"  etc.,  etc. 

WITH     INTRODUCTORY    CHAPTER     BY 

OCTAVE  CHANUTE,  C.  E.. 

President  Aero  Club  of  Illinois 


1910 

THE  CHARLES  C.  THOMPSON  CO.   (Not  Inc.) 
CHICAGO,  U.  S.  A. 


Copyrighted  1910 

By  THE  CHARLES  C.  THOMPSON  CO. 
(Not  Inc.) 

CHICAGO 


PREFACE. 

This  book  is  written  for  the  guidance  of  the  novice  in 
aviation — the  man  who  seeks  practical  information  as  to 
the  theory,  construction  and  operation  of  the  modern 
flying  machine.  With  this  object  in  view  the  wording 
is  intentionally  plain  and  non-technical.  It  contains  some 
propositions  which,  so  far  as  satisfying  the  experts  is 
concerned,  might  doubtless  be  better  stated  in  technical 
terms,  but  this  would  defeat  the  main  purpose  of  its  pre- 
paration. Consequently,  while  fully  aware  of  its  short- 
comings in  this  respect,  the  authors  have  no  apologies  to 
make. 

In  the  stating  of  a  technical  proposition  so  it  may  be 
clearly  understood  by  people  not  versed  in  technical  mat- 
ters it  becomes  absolutely  necessary  to  use  language 
much  different  from  that  which  an  expert  would  employ, 
and  this  has  been  done  in  this  volume. 

No  man  of  ordinary  intelligence  can  read  this  book 
without  obtaining  a  clear,  comprehensive  knowledge  of 
flying  machine  construction  and  operation.  He  will 
learn,  not  only  how  to  build,  equip,  and  manipulate  an 
aeroplane  in  actual  flight,  but  will  also  gain  a  thorough 
understanding  of  the  principle  upon  which  the  suspension 
in  the  air  of  an  object  much  heavier  than  the  air  is  made 
possible. 

This  latter  feature  should  make  the  book  of  interest 
even  to  those  who  have  no  intention  of  constructing  or 
operating  a  flying  machine.  It  will  enable  them  to  bet- 


203806 


4   '  FLYING   MACHINES: 

ter  understand  and  appreciate  the  performances  of  the 
daring  men  like  the  Wright  brothers;  Curtiss,  Bleriot, 
Farman,  Paulhan,  Latham,  and  others,  whose  bold  ex- 
periments have  made  aviation  an  actuality. 

For  those  who  wish  to  engage  in  the  fascinating  pas- 
time of  construction  and  operation  it  is  intended  as  a 
reliable,  practical  guide. 

It  may  be  well  to  explain  that  the  sub-headings  in  the 
articles  by  Mr.  Chanute  were  inserted  by  the  authors 
without  his  knowledge.  The  purpose  of  this  was  merely 
to  preserve  uniformity  in  the  typography  of  the  book. 
This  explanation  is  made  in  justice  to  Mr.  Chanute. 

THE  AUTHORS. 


The  authors  desire  to  make  acknowledgment  of  many  courtesies 
in  the  way  of  valuable  advice,  information,  etc.,  extended  by  Mr. 
Octave  Chanute,  C.  E.,  Mr.  E.  L.  Jones,  Editor  of  Aeronautics,  and 
the  publishers  of  the  New  England  Automobile  Journal  and  Fly. 


CONTENTS 


Chapter  Page 

I.  Evolution  of  the  Two-Surface  Flying  Machine 7 

Introductory  Chapter  by  Octave  Chanute,  C.  E. 

II.  Theory,  Development  and  Use 19 

Origin  of  the  Aeroplane — Developments  by  Chanute 
and  the  Wrights — Practical  Uses  and  Limits. 

III.  Mechanical  Bird  Action  23 

What  the  Motor  Does — Puzzle  in  Bird  Soaring. 

IV.  Various  Forms  of  Flying  Machines   29 

Helicopters,  Ornithopters  and  Aeroplanes — Mono- 
planes, Biplanes  and  Triplanes. 

V.  Constructing  a   Gliding  Machine    33 

Plans  and  Materials  Required — Estimate  of  Cost — 
Sizes  and  Preparation  of  Various  Parts — Putting  the 
Parts  Together. 

VI.  Learning  to    Fly    47 

How  to  Use  the  Glider — Effect  of  Body  Movements 
— Rules  for  Beginners — Safest  Place  to  Glide. 

VII.  Putting  On  the  Rudder 57 

Its    Construction,    Application    and   Use. 

VIII.  The  Real  Flying  Machine   61 

Surface  Area  Required — Proper  Size  of  Frame  and 
Auxiliaries — Installation  of  Motor — Cost  of  Con- 
structing Machine. 

IX.  Selection    of  the   Motor 83 

Essential  Features — Multiplicity  of  Cylinders — Power 
Required — Kind  and  Action  of  Propellers — Placing 
of  the  Motor. 

X.  Proner  Dimensions  of  Machines 101 

Figuring  Out  the  Details — How  to  Estimate  Load 
Capacity — Distribution  of  the  Weight — Measurements 
of  Leading  Machines. 


CONTENTS 

Chapter                                                                                                    Page 
XL          Plane  and  Rudder  Control 109 

Various    Methods    In    Use— Wheels    and    Hand    and 

Foot  Levers. 

XII.  How   to    Use   the   Machine 115 

Rules  of  Leading  Aviators — Rising  From  the  Ground 
— Reasonable  Altitude — Preserving  Equilibrium — 
Learning  to  Steer. 

XIII.  Peculiarities  of  Aeroplane  Power 123 

Pressure  of  the  Wind — How  to  Determine  Upon 
Power — Why  Speed  Is  Required — Bird  and  Flying 
Machine  Areas. 

XIV.  About  Wind   Currents,   Etc 133 

Uncertainty  of  Direct  Force — Trouble  With  Gusty 
Currents — Why  Bird  Action  Is  Imitated. 

XV.  The  Element  of  Danger 141 

Risk  Small  Under  Proper  Conditions — Two  Fields 
of  Safety — Lessons  in  Recent  Accidents. 

XVI.  Radical  Changes  Being  Made 145 

Results  of  Recent  Experiments — New  Dimensions — 
Increased  Speed — The  One  Governing  Rule. 

XVII.  Some   of   the   New   Designs 155 

Automatic  Control  of  Plane  Stability — Inventor  Her- 
ring's Devices — Novel  Ideas  of  Students. 

XVIII.  Demand  for  Flying  Machines 163 

Wonderful  Results  in  a  Year — Factories  Overcrowded 
with  Orders. 

XIX.  Law   of  the   Airship 169 

Rights  of  Property  Owners — Some  Legal  Pecu- 
liarities— Danger  of  Trespass. 

XX.  Soaring    Flight     179 

What   We   Can  Learn   From   Birds. 

XXI.  Flying  Machines  vs.   Balloons 191 

Advantages  and  Disadvantages   of   Each. 

XXII.  Problems    of    Aerial    Flight IQ7 

XXIII.  Amateurs  May  Use  Wright  Patents 205 

XXIV.  Hints   on    Propeller    Construction 213 

XXV.  Glossary  of  Aeronautical  Terms 219 


EVOLUTION  OF  TWO-SURFACE  FLYING 
MACHINE. 

By  Octave  Chanute. 

I  am  asked  to  set  forth  the  development  of  the  "two- 
surface"  type  of  flying  machine  which  is  now  used  with 
modifications  by  Wright  Brothers,  Farman,  *Delagrange, 
Herring  and  others. 

This  type  originated  with   Mr.   F.   H.   Wenham,  who 


Gliding  Machine  Used  by  Pilcher. 

patented  it  in  England  in  1866  (No.  1571),  taking  out 
provisional  papers  only.  In  the  abridgment  of  British 
patent  Aeronautical  Specifications  (1893)  it  is  described 
as  follows : 

"Two  or  more  aeroplanes  are  arranged  one  above  the 
other,  and  support  a  framework  or  car  containing  the 
motive  power:  The  aeroplanes  are  made  of  silk  or  can- 
vas stretched  on  a  frame  by  wooden  rods  or  steel  ribs. 
When  manual  power  is  employed  the  body  is  placed 
horizontally,  and  oars  or  propellers  are  actuated  by  the 
arms  or  legs. 

*Now  dead. 


8  FLYING  MACHINES: 

"A  start  may  be  obtained  by  lowering  the  legs  and 
running  down  hill,  or  the  machine  may  be  started  from 
a  moving  carriage.  One  or  more  screw  propellers  may 
be  applied  for  pro'pelling  when  steam  power  is  em- 
ployed." 

On  June  27,  1866,  Mr.  Wenham  read  before  the  "Aero- 
nautical Society  of  Great  Britain,"  then  recently  organ- 
ized, the  ablest  paper  ever  presented  to  that  society,  and 
thereby  breathed  into  it  a  spirit  which  has  continued  to 
this  day.  In  this  paper  he  described  his  observations  of 
birds,  discussed  the  laws  governing  flight  as  to  the  sur- 
faces and  power  required  both  with  wings  and  screws, 
and  he  then  gave  an  account  of  his  own  experiments  with 
models  and  with  aeroplanes  of  sufficient  size  to  carry 
the  weight  of  a  man. 

Second   Wenham   Aeroplane. 

His  second  aeroplane  was  sixteen  feet  from  tip  to  tip. 
A  trussed  spar  at  the  bottom  carried  six  superposed 
bands  of  thin  holland  fabric  fifteen  inches  wide,  con- 
nected with  vertical  webs  of  holland  two  feet  apart,  thus 
virtually  giving  a  length  of  wing  of  ninety-six  feet  and 
one  hundred  and  twenty  square  feet  of  supporting  sur- 
face. The  man  was  placed  horizontally  on  a  base  board 
beneath  the  spar.  This  apparatus  when  tried  in  the  wind 
was  found  to  be  unmanageable  by  reason  of  the  fluttering 
motions  of  the  fabric,  which  was  insufficiently  stiffened 
with  crinoline  steel,  but  Mr.  Wenham  pointed  out  that 
this  in  no  way  invalidated  the  principle  of  the  apparatus, 
which  was  to  obtain  large  supporting  surfaces  without 
increasing  unduly  the  leverage  and  consequent  weight 
of  spar  required,  by  simply  superposing  the  surfaces. 

This  principle  is  entirely  sound  and  it  is  surprising  that 
it  is,  to  this  day,  not  realized  by  those  aviators  who  are 
hankering  for  monoplanes. 


CONSTRUCTION  AND   OPERATION  9 

Experiments  by  Stringfellow. 

The  next  man  to  test  an  apparatus  with  superposed 
surfaces  was  Mr.  Stringfellow,  who,  becoming1  much  im- 
pressed with  Mr.  Wenham's  proposal,  produced  a  largish 
model  at  the  exhibition  of  the  Aeronautical  Society  in 
1868.  It  consisted  of  three  superposed  surfaces  aggre- 


One  of  the  First  Hargrave  Kites. 


gating  28  square  feet  and  a  tail  of  8  square  feet  more. 
The  weight  was  under  12  pounds  and  it  was  driven  by  a 
central  propeller  actuated  by  a  steam  engine  overesti- 
mated at  one-third  of  a  horsepower.  It  ran  suspended 
to  a  wire  on  its  trials  but  failed  of  free  flight,  in  conse- 
quence of  defective  equilibrium.  This  apparatus  has 
since  been  rebuilt  and  is  now  in  the  National  Museum 
of  the  Smithsonian  Institution  at  Washington, 


10  FLYING   MACHINES: 

Linfield's   Unsuccessful   Efforts. 

In  1878  Mr.  Linfield  tested  an  apparatus  in  England 
consisting  of  a  cigar-shaped  car,  to  which  was  attached 
on  each  side  frames  five  feet  square,  containing  each 
twenty-five  superposed  planes  of  stretched  and  varnished 
linen  eighteen  inches  wide,  and  only  two  inches  apart, 
thus  reminding  one  of  a  Spanish  donkey  with  panniers. 
The  whole  weighed  two  hundred  and  forty  pounds.  This 
was  tested  by  being  mounted  on  a  flat  car  behind  a  loco- 
motive going  40  miles  an  hour.  When  towed  by  a  line 
fifteen  feet  long  the  apparatus  rose  only  a  little  from  the 
car  and  exhibited  such  unstable  equilibrium  that  the  ex- 
periment was  not  renewed.  The  lift  was  only  about  one- 
third  of  what  it  would  have  been  had  the  planes  been 
properly  spaced,  say  their  full  width  apart,  instead  of 
one-ninth  as  erroneously  devised. 

Renard's  "Dirigible  Parachute." 

In  1889  Commandant  Renard,  the  eminent  superin- 
tendent of  the  French  Aeronautical  Department,  exhib- 
ited at  the  Paris  Exposition  of  that  year,  an  apparatus 
experimented  with  some  years  before,  which  he  termed 
a  "dirigible  parachute."  It  consisted  of  an  oviform  body 
to  which  were  pivoted  two  upright  slats  carrying  above 
the  body  nine  long  superposed  flat  blades  spaced  about 
one-third  of  their  width  apart.  When  this  apparatus 
was  properly  set  at  an  angle  to  the  longitudinal  axis  of 
the  body  and  dropped  from  a  balloon,  it  travelled  back 
against  the  wind  for  a-  considerable  distance  before 
alighting.  The  course  could  be  varied  by  a  rudder.  *No 
practical  application  seems  to  have  been  made  of  this 
device  by  the  French  War  Department,  but  Mr.  J.  P. 
Holland,  the  inventor  of  the  submarine  boat  whict  bears 
his  name,  proposed  in  1893  an  arrangement  of  pivoted 


CONSTRUCTION  AND   OPERATION 


11 


framework  attached  to  the  body  of  a  flying  machine 
which  combines  the  principle  of  Commandant  Renard 
with  the  curved  blades  experimented  with  by  Mr.  Phil- 
lips, now  to  be  noticed,  with  the  addition  of  lifting  screws 
inserted  among  the  blades. 

Phillips  Fails  on  Stability  Problem. 

In  1893  Mr.  Horatio  Phillips,  of  England,  after  some 
very  interesting  experiments  with  various  wing  sections, 
from  which  he  deduced  conclusions  as  to  the  shape  of 


Hargrave  Kite  With  Vibrating  Wings. 

maximum  lift,  tested  an  apparatus  resembling  a  Vene- 
tian blind  which  consisted  of  fifty  wooden  slats  of 
peculiar  shape,  22  feet  long,  one  and  a  half  inches  wide, 
and  two  inches  apart,  set  in  ten  vertical  upright  boards. 
All  this  was  carried  upon  a  body  provided  with  three 
wheels.  It  weighed  420  pounds  and  was  driven  at  40 
miles  an  hour  on  a  wooden  sidewalk  by  a  steam  engine 
of  nine  horsepower  which  actuated  a  two-bladed  screw. 
The  lift  was  satisfactory,  being  perhaps  70  pounds  per 
horsepower,  but  the  equilibrium  was  quite  bad  and  the 
experiments  were  discontinued.  They  were  taken  up 
again  in  1904  with  a  similar  apparatus  large  enough  to 
carry  a  passenger,  but  the  longitudinal  equilibrium  was 
found  to  be  defective.  Then  in  1907  a  new  machine  was 


12  FLYING   MACHINES: 

tested,  in  which  four  sets  of  frames,  carrying  similar  sets 
of  slat  "sustainers"  were  inserted,  and  with  this  arrange- 
ment the  longitudinal  stability  was  found  to  be  very  sat- 
isfactory. The  whole  apparatus,  with  the  operator, 
weighed  650  pounds.  It  flew  about  200  yards  when 
driven  by  a  motor  of  20  to  22  h.p.  at  30  miles  an  hour, 
thus  exhibiting  a  lift  of  about  32  pounds  per  h.p.,  while 
it  will  be  remembered  that  the  aeroplane  of  Wright 
Brothers  exhibits  a  lifting  capacity  of  50  pounds  to 
the  h.p. 

Hargrave's  Kite  Experiments. 

After  experimenting  with  very  many  models  and 
building  no  less  than  eighteen  monoplane  flying  model 
machines,  actuated  by  rubber,  by  compressed  air  and  by 
steam,  Mr.  Lawrence  Hargrave,  of  Sydney,  New  South 
Wales,  invented  the  cellular  kite  which  bears  his  name 
and  made  it  known  in  a  paper  contributed  to  the  Chi- 
cago Conference  on  Aerial  Navigation  in  1893,  describ- 
ing several  varieties.  The  modern  construction  is  well 
known,  arid  consists  of  two  cells,  each  of  superposed  sur- 
faces with  vertical  side  fins,  placed  one  behind  the  other 
and  connected  by  a  rod  or  frame.  This  flies  with  great 
steadiness  without  a  tail.  Mr.  Hargrave's  idea  wras  to 
use  a  team  of  these  kites,  below  which  he  proposed  to 
suspend  a  motor  and  propeller  from  which  a  line  would 
be  carried  to  an  anchor  in  the  ground.  Then  by  actu- 
ating the  propeller  the  whole  apparatus  would  move 
forward,  pick  up  the  anchor  and  fly  away.  He  said: 
"The  next  step  is  clear  enough,  namely,  that  a  flying 
machine  with  acres  of  surface  can  be  safely  got  under 
way  or  anchored  and  hauled  to  the  ground  by  means  of 
the  string  of  kites." 

The  first  tentative  experiments  did  not  result  well  and 
emphasized  the  necessity  for  a  light  motor,  so  that  Mr. 
Hargrave  has  since  been  engaged  in  developing  one,  not 


CONSTRUCTION  AND   OPERATION 


13 


having  convenient  access  to  those  which  have  been  pro- 
duced by  the  automobile  designers  and  builders. 

Experiments   With   Glider  Model. 

And  here  a  curious  reminiscence  may  be  indulged  in. 
In  1888  the  present  writer  experimented  with  a  two-cell 


Glider  of  Lilienthal  Type. 

gliding  model,  precisely  similar  to  a  Hargrave  kite,  as 
will  be  confirmed  by  Mr.  Herring.  It  was  frequently 
tested  by  launching  from  the  top  of  a  three-story  house 
and  glided  downward  very  steadily  in  all  sorts  of  breezes, 
but  the  angle  of  descent  was  much  steeper  than  that  of 
birds,  and  the  weight  sustained  per  square  foot  was  less 
than  with  single  cells,  in  consequence  of  the  lesser  sup- 
port afforded  by  the  rear  cell,  which  operated  upon  air 


14  FLYING   MACHINES: 

already  set  in  motion  downward  by  the  front  cell,  so 
nothing  more  was  done  with  it,  for  it  never  occurred  to 
the  writer  to  try  it  as  a  kite  and  he  thus  missed  the  dis- 
tinction which  attaches  to  Hargrave's  name. 

Sir  Hiram  Maxim  also  introduced  fore  and  aft  super- 
posed surfaces  in  his  wondrous  flying  machine  of  1893, 
but  he  relied  chiefly  for  the  lift  upon  his  main  large  sur- 
face and  this  necessitated  so  many  guys,  to  prevent  dis- 
tortion, as  greatly  to  increase  the  head  resistance  and 
this,  together  with  the  unstable  equilibrium,  made  it 
evident  that  the  design  of  the  machine  would  have  to 
be  changed. 

How  Lilienthal  Was  Killed. 

In  1895,  Otto  Lilienthal,  the  father  of  modern  aviation, 
the  man  to  whose  method  of  experimenting  almost  all 
present  successes  are  due,  after  making  something  like 
two  thousand  glides  with  monoplanes,  added  a  super- 
posed surface  to  his  apparatus  and  found  the  control  of 
it  much  improved.  The  two  surfaces  were  kept  apart 
by  two  struts  or  vertical  posts  with  a  few  guy  wires,  but 
the  connecting  joints  were  weak  and  there  was  nothing 
like  trussing.  This  eventually  cost  his  most  useful  life. 
Two  weeks  before  that  distressing  loss  to  science,  Herr 
Wilhelm  Kress,  the  distinguished  and  veteran  aviator 
of  Vienna,  witnessed  a  number  of  glides  by  Lilienthal 
with  his  double-decked  apparatus.  He  noticed  that  it 
was  much  wracked  and  wobbly  and  wrote  to  me  after 
the  accident :  "The  connection  of  the  wings  and  the 
steering  arrangement  were  very  bad  and  unreliable.  I 
warned  Herr  Lilienthal  very  seriously.  He  promised 
me  that  he  would  soon  put  it  in  order,  but  I  fear  that  he 
did  not  attend  to  it  immediately." 

In  point  of  fact,  Lilienthal  had  built  a  new  machine, 
upon  a  different  principle,  from  which  he  expected  great 
results,  and  intended  to  make  but  very  few  more  flights 


CONSTRUCTION   AND    OPERATION  15 

with  the  old  apparatus.  He  unwisely  made  one  too 
many  and,  like  Pilcher,  was  the  victim  of  a  distorted 
apparatus.  Probably  one  of  the  joints  of  the  struts 
gave  way,  the  upper  surface  blew  back  and  Lilienthal, 
who  was  well  forward  on  the  lower  surface,  was  pitched 
headlong  to  destruction. 

Experiments  by  the  Writer. 

In   1896,   assisted  by   Mr.  Herring  and   Mr.   Avery,   I 
experimented  with   several  full   sized  gliding  machines, 


Prof.  Langley's  Aerodrome. 

carrying  a  man.  The  first  was  a  Lilienthal  monoplane, 
which  was  deemed  so  cranky  that  it  was  discarded  after 
making  about  one  hundred  glides,  six  weeks  before 
Lilienthal's  accident.  The  second  was  known  as  the 
multiple  winged  machine  and  finally  developed  into  five 
pairs  of  pivoted  wings,  trussed  together  at  the  front  and 


16  FLYING   MACHINES: 

one  pair  in  the  rear.  It  glided  at  angles  of  descent  of 
10  or  ii  degrees  or  of  one  in  five,  and  this  was  deemed 
too  steep.  Then  Mr.  Herring  and  myself  made  compu- 
tations to  analyze  the  resistances.  We  attributed  much 
of  them  to  the  five  front  spars  of  the  wings  and  on  a 
sheet  of  cross-barred  paper  I  at  once  drew  the  design  for 
a  new  three-decked  machine  to  be  built  by  Mr.  Herring. 
Being  a  builder  of  bridges,  I  trussed  these  surfaces 
together,  in  order  to  obtain  strength  and  stiffness.  When 
tested  in  gliding  flight  the  lower  surface  \vas  found  too 
near  the  ground.  It  was  taken  off  and  the  remaining 
apparatus  now  consisted  of  two  surfaces  connected  to- 
gether by  a  girder  composed  of  vertical  posts  and  diag- 
onal ties,  specifically  known  as  a  "Pratt  truss.''  Then 
Mr.  Herring  and  Mr.  Avery  together  devised  and  put 
on  an  elastic  attachment  to  the  tail.  This  .machine 
proved  a  success,  it  being  safe  and  manageable.  Over 
700  glides  wrere  made  with  it  at  angles  of  descent  of  8 
to  10  degrees,  or  one  in  six  to  one  in  seven. 

First  Proposed  by  Wenham. 

The  elastic  tail  attachment  and  the  trussing  of  the 
connecting  frame  of  the  superposed  wings  were  the  only 
novelties  in  this  machine,  for  the  superposing  of  the 
surfaces  had  first  been  proposed  by  Wenham,  but  in 
accordance  with  the  popular  perception,  which  bestows 
all  the  credit  upon  the  man  who  adds  the  last  touch 
making  for  success  to  the  labors  of  his  predecessors,  the 
machine  has  since  been  known  by  many  persons  as  the 
"Chanute  type"  of  gliders,  much  to  my  personal  grati- 
fication. 

It  has  since  been  improved  in  many  ways.  Wright 
Brothers,  disregarding  the  fashion  which  prevails  among 
birds,  have  placed  the  tail  in  front  of  their  apparatus  and 
called  it  a  front  rudder,  besides  placing  the  operator  in 


CONSTRUCTION   AND    OPERATION  17 

horizontal  position  instead  of  upright,  as  I  did;  and  also 
providing  a  method  of  warping  the  wings  to  preserve 
equilibrium.  Farman  and  Delagrange,  under  the  very 
able  guidance  and  constructive  work  of  Voisin  brothers, 
then  substituted  many  details,  including  a  box  tail  for 
the  dart-like  tail  which  1  used.  This  may  have  increased 
the  resistance,  but  it  adds  to  the  steadiness.  Now  the 


Chanute's    Multiplane    Glider. 

tendency  in  France  seems  to  be  to  go  back  to  the  mono- 
plane. 

Monoplane   Idea   Wrong. 

The  advocates  of  the  single  supporting  surface  are 
probably  mistaken.  It  is  true  that  a  single  surface 
shows  a  greater  lift  per  square  foot  than  superposed 
surfaces  for  a  given  speed,  but  the  increased  weight  due 
to  leverage  more  than  counterbalances  this  advantage  by 
requiring  heavy  spars  and  some  guys.  I  believe  that 
the  future  aeroplane  dynamic  flier  will  consist  of  super- 
posed surfaces,  and,  now  that  it  has  been  found  that  by 


18  FLYING   MACHINES: 

imbedding  suitably  shaped  spars  in  the  cloth  the  head 
resistance  may  be  much  diminished,  I  see  few  objections 
to  superposing  three,  four  or  even  five  surfaces  properly 
trussed,  and  thus  obtaining  a  compact,  handy,  manage- 
able and  comparatively  light  apparatus.* 

*Aeronautics. 


CHAPTER  II. 


THEORY,  DEVELOPMENT,  AND  USE. 

While  every  craft  that  navigates  the  air  is  an  air- 
ship, all  airships  are  not  flying  machines.  The  balloon, 
for  instance,  is  an  airship,  but  it  is  not  what  is  known 
among  aviators  as  a  flying  machine.  This  latter  term 
is  properly  used  only  in  referring  to  heavier-than-air 
machines  which  have  no  gas-bag  lifting  devices,  and  are 


Imitation  of  Bird  In  Aeroplane  Design. 

made  to  really  fly  by  the  application  of  engine  propul- 
sion. 

Are  Mechanical  Birds. 

All  successful  flying  machines — and  there  are  a  num- 
ber of  them — are  based  on  bird  action.  The  various 
designers  have  studied  bird  flight  and  soaring,  mastered 
its  technique  as  devised  by  Nature,  and  the  modern  fly- 
ing machine  is  the  result.  On  an  exaggerated,  enlarged 
scale,  the  machines  which  are  now  navigating  the  air 
are  nothing  more  nor  less  than  mechanical  birds. 

19 


20  FLYING    MACHINES: 

Origin  of  the  Aeroplane. 

Octave  Chanttte,  of  Chicago,  may  well  be  called  "the 
developer  of  the  flying  machine."  Leaving  balloons  and 
various  forms  of  gas-bags  out  of  consideration,  other 
experimenters,  notably  Langley  and  Lilienthal,  ante- 
dated him  in  attempting  the  navigation  of  the  air  on 
aeroplanes,  or  flying  machines,  but  none  of  them  were 
wholly  successful,  and  it  remained  for  Chanute  to  dem- 
onstrate the  practicability  of  what  was  then  called  the 
gliding  machine.  This  term  was  adopted  because  the 
apparatus  was,  as  the  name  implies,  simply  a  gliding 
machine,  being  without  motor  propulsion,  and  intended 
solely  to  solve  the  problem  of  the  best  form  of  con- 
struction. The  biplane,  used  by  Chanute  in  1896,  is 
still  the  basis  of  most  successful  flying  machines,  the 
only  radical  difference  being  that  motors,  rudders,  etc., 
have  been  added. 

,  Character  of  Chanute's  Experiments. 

It  was  the  privilege  of  the  author  of  this  book  to  be 
Mr.  Chanute's  guest  at  Millers,  Indiana,  in  1896,  when, 
in  collaboration  with  Messrs.  Herring  and  Av.ery,  he  was 
conducting  the  series  of  experiments  which  have  since 
made  possible  the  construction  of  the  modern  flying 
machine  which  such  successful  aviators  as  the  Wright 
brothers  and  others  are  now  using.  It  was  a  wild 
country,  much  frequented  by  eagles,  hawks,  and  similar 
birds.  The  enthusiastic  trio,  Chanute,  Herring  and 
Avery,  would  watch  for  hours  the  evolutions  of  some 
big  bird  in  the  air,  agreeing  in  the  end  on  the  verdict, 
"When  we  master  the  principle  of  that  bird's  soaring 
without  wing  action,  we  will  have  come  close  to  solving 
the  problem  of  the  flying  machine." 

Aeroplanes  of  various  forms  were  constructed  by  Mr. 


CONSTRUCTION  AND    OPERATION  21 

Chanute  with  the  assistance  of  Messrs.  Herring  and 
Avery  until,  at  the  time  of  the  writer's  visit,  they  had 
settled  upon  the  biplane,  or  two-surface  machine.  Mr. 
Herring  later  equipped  this  with  a  rudder,  and  made 
other  additions,  but  the  general  idea  is  still  the  basis  of 
the  Wright,  Curtiss,  and  other  machines  in  which,  by 
the  aid  of  gasolene  motors,  long  flights  have  been  made. 

Developments  by  the  Wrights. 
In    1900   the   Wright   brothers,    William    and   Orville, 


Chanute  Glider  Equipped  With  Rudder. 

who  were  then  in  the  bicycle  business  in  Dayton,  Ohio, 
became  interested  in  Chanute's  experiments  and  com- 
municated with  him.  The  result  was  that  the  Wrights 
took  up  Chanute's  ideas  and  developed  them  further, 
making  many  additions  of  their  own,  one  of  which  was 
the  placing  of  a  rudder  in  front,  and  the  location  of  the 


22  FLYING   MACHINES: 

operator  horizontally  on  the  machine,  thus  diminishing 
by  four-fifths  the  wind  resistance  of  the  man's  body. 
For  three  years  the  Wrights  experimented  with  the 
glider  before  venturing  to  add  a  motor,  which  was  not 
done  until  they  had  thoroughly  mastered  the  control  of 
their  movements  in  the  air.  • 

Limits  of  the  Flying  Machine. 

In  the  opinion  of  competent  experts  it  is  idle  to  look 
for  a  commercial  future  for  the  flying  machine.  There 
is,  and  always  will  be,  a  limit  to  its  carrying  capacity 
which  will  prohibit  its  employment  for  passenger  or 
freight  purposes  in  a  wholesale  or  general  way.  There 
are  some,  of  course,  who  will  argue  that  because  a 
machine  will  carry  two  people,  another  may  be  con- 
structed that  will  carry  a  dozen,  but  those  who  make 
this  contention  do  not  understand  the  theory  of  weight 
sustentation  in  the  air;  or  that  the  greater  the  load  the 
greater  must  be  the  lifting  power  (motors  and  plane 
surface),  and  that  there  is  a  limit  to  these — as  will  be 
explained  later  on — beyond  which  the  aviator  cannot  go. 

Some  Practical  Uses. 

At  the  same  time  there  are  fields  in  which  the  flying 
machine  may  be  used  to  great  advantage.  These  are: 

Sports — Flying  machine  races  or  flights  will  always 
be  popular  by  reason  of  the  element  of  danger.  It  is 
a  strange,  but  nevertheless  a  true  proposition,  that  it  is 
this  element  which  adds  zest  to  all  sporting  events. 

Scientific — For  exploration  of  otherwise  inaccessible 
regions  such  as  deserts,  mountain  tops,  etc. 

Reconnoitering — In  time  of  war  flying  machines  may 
be  used  to  advantage  to  spy  out  an  enemy's  encamp- 
ment, ascertain  its  defenses,  etc. 


CHAPTER    III. 


MECHANICAL  BIRD  ACTION. 

In  order  to  understand  the  theory  of  the  modern  flying 
machine  one  must  also  understand  bird  action  and  wind 
action.  In  this  connection  the  following  simple  expe- 
riment will  be  of  interest: 

Take  a  circular-shaped  bit  of  cardboard,  like  the  lid  of 
a  hat  box,  and  remove  the  bent-over  portion  so  as  to 
have  a  perfectly  flat  surface  with  a  clean,  sharp  edge. 
Holding  the  cardboard  at  arm's  length,  withdraw  your 


Illustrating  the   Effect  of  Motion  on  Sustentation. 
23 


24 


FL  Y1NG   MA  CHINES : 


hand,  leaving  the  cardboard  without  support.  What  is 
the  result?  The  cardboard,  being  heavier  than  air,  and 
having  nothing  to  sustain  it,  will  fall  to  the  ground. 
Pick  it  up  and  throw  it,  with  considerable  force,  against 
the  wind  edgewise.  What  happens?  Instead  of  falling 
to  the  ground,  the  cardboard  sails  along  on  the  wind, 
remaining  afloat  so  long  as  it  is  in  motion.  It  seeks 
the  ground,  by  gravity,  only  as  the  motion  ceases,  and 
then  by  easy  stages,  instead  of  dropping  abruptly  as  in 
the  first  instance. 


Illustrating   the   Effect  of  Motion   on   Sustentation. 

Here  we  have  a  homely,  but  accurate  illustration  of 
the  action  of  the  flying  machine.  The  motor  does  for 
the  latter  what  the  force  of  your  arm  does  for  the  card- 
board— imparts  a  motion  which  keeps  it  afloat.  The 
only  real  difference  is  that  the  motion  given  by  the 
motor  is  continuous  and  much  more  powerful  than  that 
given  by  your  arm.  The  action  of  the  latter  is  limited 
and  the  end  of  its  propulsive  force  is  reached  within  a 


CONSTRUCTION   AND    OPERATION 


25 


second  or  two  after  it  is  exerted,  while  the  action  of  the 
motor  is  prolonged. 

Another  Simple  Illustration. 

Another  simple  means  of  illustrating  the  principle  of 
flying  machine  operation,  so  far  as  sustentation  and  the 
elevation  and  depression  of  the  planes  is  concerned,  is 
explained  in  the  accompanying  diagram. 

A  is  a  piece  of  cardboard  about  2  by  3  inches  in  size. 
B  is  a  piece  of  paper  of  the  same  size  pasted  to  one  edge 
of  A.  If  you  bend  the  paper  to  a  curve,  with  convex 
side  up  and  blow  across  it  as  shown  in  Figure  C,  the 
paper  will  rise  instead  of  being  depressed:  The  dotted 
lines  show  that  the  air  is  passing  over  the  top  of  the 
curved  paper  and  yet,  no  matter  how  hard  you  may 


F«,    D 

Principle  Upon  Which  Aeroplane  Works. 


26  FLYING   MACHINES: 

blow,  the  effect  will  be  to  elevate  the  paper,  despite  the 
fact  that  the  air  is  passing  over,  instead  of  under  the 
curved  surface. 

In  Figure  D  we  have  an  opposite  effect.  Here  the 
paper  is  in  a  curve  exactly  the  reverse  of  that  shown  in 
Figure  C,  bringing  the  concave  side  up.  Now  if  you 
will  again  blow  across  the  surface  of  the  card  the  action 
of  the  paper  will  be  downward — it  will  be  impossible  to 
make  it  rise.  The  harder  you  blow  the  greater  will  be 
the  downward  movement. 

Principle  In  General  Use. 

This  principle  is  taken  advantage  of  in  the  construc- 
tion of  all  successful  flying  machines.  Makers  of  mono- 
planes and  biplanes  alike  adhere  to  curved  bodies,  with 
the  concave  surface  facing  downward.  Straight  planes 
were  tried  for  a  time,  but  found  greatly  lacking  in  the 
power  of  sustentation.  By  curving  the  planes,  and  plac- 
ing the  concave  surface  downward,  a  sort  of  inverted  bowl 
is  formed  in  which  the  air  gathers  and  exerts  a  buoyant 
effect.  Just  what  the  ratio  of  the  curve  should  be  is  a 
matter  of  contention.  In  some  instances  one  inch  to  the 
foot  is  found  to  be  satisfactory;  in  others  this  is  doubled, 
and  there  are  a  few  cases  in  which  a  curve  of  as  much  as 
3  inches  to  the  foot  has  been  used. 

Right  here  it  might  be  well  to  explain  that  the  word 
"plane"  applied  to  Hying  machines  of  modern  construc- 
tion is  in  reality  a  misnomer.  Plane  indicates  a  flat, 
level  surface.  As  most  successful  flying  machines  have 
curved  supporting  surfaces  it  is  clearly  wrong  to  speak 
of  "planes,"  or  "aeroplanes."  Usage,  however,  has  made 
the  terms  convenient  and,  as  they  are  generally  accepted 
and  understood  by  the  public,  they  are  used  in  like  man- 
in  this  volume. 


CONSTRUCTION   AND    OPERATION 


27 


Getting  Under  Headway.    . 

A  bird,  on  first  rising  from  the  ground,  or  beginning 
its  flight  from  a  tree,  will  flap  its  wings  to  get  under 
headway.  Here  again  we  have  another  illustration  of 
the  manner  in  which  a  flying  machine  gets  under  head- 
way— the  motor  imparts  the  force  necessary  to  put  the 
machine  into  the  air,  but  right  here  the  similarity  ceases. 
If  the  machine  is  to  be  kept  afloat  the  motor  must  be 
kept  moving.  A  flying  machine  will  not  sustain  itself ; 
it  will  not  remain  suspended  in  the  air  unless  it  is 
under  headway.  This  is  because  it  is  heavier  than  air, 
and  gravity  draws  it  to  the  ground. 


How  Machines   Imitate   Birds. 

A — bird  and  machine  both  on  straight  line;  B — bird  and  machine 
ascending  by  elevation  of  head;  C — bird  and  machine  descending 
by  depression  of  head. 

Puzzle   in   Bird   Soaring. 

But  a  bird,  which  is  also  heavier  than  air,  will  remain 
suspended,  in  a  calm,  will  even  soar  and  move  in  a 
circle,  without  apparent  movement  of  its  wings.  This 
is  explained  on  the  theory  that  there  are  generally  ver- 
tical columns  of  air  in  circulation  strong  enough  to  sus- 
tain a  bird,  but  much  too  weak  to  exert  any  lifting  power 
on  a  flying  machine.  It  is  easy  to  understand  how  a 


28  FLYING    MACHINES: 

bird  can  remain  suspended  when  the  wind  is  in  action, 
but  its  suspension  in  a  seeming  dead  calm  was  a  puzzle 
to  scientists  until  Mr.  Chanute  advanced  the  proposition 
of  vertical  columns  of  air. 

Modeled   Closely  After  Birds. 

So  far  as  possible,  builders  of  flying  machines  have 
taken  what  may  be  called  "the  architecture"  of  birds  as 
a  model.  This  is  readily  noticeable  in  the  form  of  con- 
struction. When  a  bird  is  in  motion  its  wings  (except 
when  flapping)  are  extended  in  a  straight  line  at  right 
angles  to  its  body.  This  brings  a  sharp,  thin  edge 
against  the  air,  offering  the  least  possible  surface  for 
resistance,  while  at  the  same  time  a  broad  surface  for 
support  is  afforded  by  the  flat,  under  side  of  the  wings. 
Identically  the  same  thing  is  done  in  the  construction  of 
the  flying  machine. 

'  Note,  for  instance,  the  marked  similarity  in  form  as 
shown  in  the  illustration  in  Chapter  II.  Here  A  is  the 
bird,  and  B  the  general  outline  of  the  machine.  The 
thin  edge  of  the  plane  in  the  latter  is  almost  a  duplicate 
of  that  formed  by  the  outstretched  wings  of  the  bird, 
while  the  rudder  plane  in  the  rear  serves  the  same  pur- 
pose as  the  bird's  tail. 


CHAPTER    IV. 


VARIOUS    FORMS    OF    FLYING    MACHINES. 

There  are  three  distinct  and  radically  different  forms 
of  flying  machines.  These  are : 

Aeroplanes,   helicopters   and   ornithopers. 

Of  these  the  aeroplane  takes  precedence  and  is  used 
almost  exclusively  by  successful  aviators,  the  helicopters 
and  ornithopers  having  been  tried  and  found  lacking  in 
some  vital  features,  while  at  the  same  time  in  some 
respects  the  helicopter  has  advantages  not  found  in  the 
aeroplane. 

What  the   Helicopter  Is. 

The  helicopter  gets  its  name  from  being  fitted  with 
vertical  propellers  or  helices  (see  illustration)  by  the 


General   Outline  of  Helicopter  Machine. 

action  of  which  the  machine  is  raised  directly  from  the 
ground  into  the  air.  This  does  away  with  the  necessity 
for  getting  the  machine  under  a  gliding  headway  before 

29 


30  FLYING   MACHINES: 

it  floats,  as  is  the  case  with  the  aeroplane,  and  conse- 
quently the  helicopter  can  be  handled  in  a  much  smaller 
space  than  is  required  for  an  aeroplane.  This,  in  many 
instances,  is  an  important  advantage,  but  it  is  the  only 
one  the  helicopter  possesses,  and  is  more  than  overcome 
by  its  drawbacks.  The  most  serious  of  these  is  that  the 
helicopter  is  deficient  in  sustaining  capacity,  and  requires 
too  much  motive  power. 

Form  of  the  Ornithopter. 

The  ornithopter  has  hinged  planes  which  work  like 
the  wings  of  a  bird.  At  first  thought  this  would  seem 
to  be  the  correct  principle,  and  most  of  the  early  exper- 
imenters conducted  their  operations  on  this  line.  It 


Ader's    Ornithopter    Constructed   in    1882. 

is  now  generally  understood,  however,  that  the  bird  in 
soaring  is  in  reality  an  aeroplane,  its  extended  wings 
serving  to  sustain,  as  well  as  propel,  the  body.  At  any 
rate  the  ornithoper  has  not  been  successful  in  aviation, 
and  has  been  interesting  mainly  as  an  ingenious  toy. 
Attempts  to  construct  it  on  a  scale  that  would  permit 
of  its  use  by  man  in  actual  aerial  flights  have  been  far 
from  encouraging. 

Three  Kinds  of  Aeroplanes. 

There -are  three  forms  of  aeroplanes,  with  all  of  which 
more  or  less  success  has  been  attained.     These  are: 


CONSTRUCTION   AND    OPERATION  31 

The  monoplane,  a  one-surfaced  plane,  like  that  used 
by  Bleriot. 

The  biplane,  a  two-surfaced  plane,  now  used  by  the 
Wrights,  Curtiss,  Farman,  and  others. 

The  triplane,  a  three-surfaced  plane.  This  form  is 
but  little  used,  its  only  prominent  advocate  at  present 
being  Elle  Lavimer,  a  Danish  experimenter,  who  has  not 
thus  far  accomplished  much. 

Whatever  of  real   success   has   been   accomplished  in 


A  Modern  Form  of  Monoplane. 

aviation  may  be  credited  to  the  monoplane  and  biplane, 
with  the  balance  in  favor  of  the  latter.  The  monoplane 
is  the  more  simple  in  construction  and,  where  weight- 
sustaining  capacity  is  not  a  prime  requisite,  may  prob- 
ably be  found  the  most  convenient.  This  opinion  is 
based  on  the  fact  that  the  smaller  the  surface  of  the 
plane  the  less  will  be  the  resistance  offered  to  the  air, 
and  the  greater  will  be  the  speed  at  which  the  machine 
may  be  moved.  On  the  other  hand,  the  biplane  has  a 
much  greater  plane  surface  (double  that  of  a  monoplane 


32 


FLYING    MACHINES: 


of  the  same  size)  and  consequently  much  greater  weight- 
carrying  capacity. 

Differences  in  Biplanes. 

While  all  biplanes  are  of  the  same  general  construc- 
tion so  far  as  the  main  planes  are  concerned,  each  aviator 
has  his  own  ideas  as  to  the  "rigging." 

Wright,  for  instance,  places  a  double  horizontal  rud- 
der in  front,  with  a  vertical  rudder  in  the  rear.  There 
are  no  partitions  between  the  main  planes,  and  the 
bicycle  wheels  used  on  other  forms  are  replaced  by  skids. 


Biplane  Used  by  Delagrange. 

Voisin,  on  the  contrary,  divides  the  main  planes  with 
vertical  partitions  to  increase  stability  in  turning;  uses 
a  single-plane  horizontal  rudder  in  front,  and  a  big  box- 
tail  with  vertical  rudder  at  the  rear;  also  the  bicycle 
wheels. 

Curtiss  attaches  horizontal  stabilizing  surfaces  to  the 
upper  plane ;  has  a  double  horizontal  rudder  in  front, 
with  a  vertical  rudder  and  horizontal  stabilizing  surfaces 
in  rear.  Also  the  bicycle  wheel  alighting  gear. 


CHAPTER    V. 

CONSTRUCTING  A  GLIDING  MACHINE. 

First  decide  upon  the  kind  of  a  machine  you  want — 
monoplane,  biplane,  or  triplane.  For  a  novice  the  bi- 
plane will,  as  a  rule,  be  found  the  most  satisfactory  as 
it  is  more  compact  and  therefore  the  more  easily  handled. 
This  will  be  easily  understood  when  we  realize  that  the 
surface  of  a  flying1  machine  should  be  laid  out  in  pro- 
portion to  the  amount  of  weight  it  will  have  to  sustain. 
The  generally  accepted  rule  is  that  152  square  feet  of 
surface  will  sustain  the  weight  of  an  average-sized  man, 
say  170  pounds.  Now  it  follows  that  if  these  152  square 
feet  of  surface  are  used  in  one  plane,  as  in  the  mono- 
plane, the  length  and  width  of  this  plane  must  be  greater 
than  if  the  same  amount  of  surface  is  secured  by  using 
two  planes — the  biplane.  This  results  in  the  biplane 
being  more  compact  and  therefore  more  readily  manip- 
ulated than  the  monoplane,  which  is  an  important  item 
for  a  novice. 

Glider  the  Basis  of  Success. 

Flying  machines  without  motors  are  called  gliders.  In 
making  a  flying  machine  you  first  construct  the  glider. 
If  you  use  it  in  this  form  it  remains  a  glider.  If  you 
install  a  motor  it  becomes  a  flying  machine.  You  must 
have  a  good  glider  as  the  basis  of  a  successful  flying 
machine. 

It  will  be  well  for  the  novice,  the  man  who  has  never 
had  any  experience  as  an  aviator,  to  begin  with  a  glider 

33 


34  FLYING   MACHINES: 

and  master  its  construction  and  operation  before  he 
essays  the  more  pretentious  task  of  handling  a  fully- 
equipped  flying  machine.  In  fact,  it  is  essential  that  he 
should  do  so. 

Plans  for  Handy  Glider. 

A  glider  with  a  spread  (advancing  edge)  of  20  feet,  and 
a  breadth  or  depth  of  4  feet,  will  be  about  right  to  begin 
with.  Two  planes  of  this  size  will  give  the  152  square 
yards  of  surface  necessary  to  sustain  a  man's  weight. 
Remember  that  in  referring  to  flying  machine  measure- 
ments "spread"  takes  the  place  of  what  would  ordinarily 
be  called  "length,"  and  invariably  applies  to  the  long 
or  advancing  edge  of  the  machine  which  cuts  into  the  air. 
Thus,  a  glider  is  spoken  of  as  being  20  feet  spread,  and 
4  feet  in  depth.  So  far  as  mastering  the  control  of  the 
machine  is  concerned,  learning  to  balance  one's  self  in 
the  air,  guiding  the  machine  in  any  desired  direction  by 
changing  the  position  of  the  body,  etc.,  all  this  may  be 
learned  just  as  readily,  and  perhaps  more  so,  with  a  20- 
foot  glider  than  with  a  larger  apparatus. 

Kind    of    Material    Required. 

There  are  three  all-important  features  in  flying  ma- 
chine construction,  viz. :  lightness,  strength  and  extreme 
rigidity.  Spruce  iss  the  wood  generally  used  for  glider 
frames.  Oak,  ash  and  hickory  are  all  stronger,  but  they 
are  also  considerably  heavier,  and  where  the  saving  of 
weight  is  essential,  the  difference  is  largely  in  favor  of 
spruce.  This  will  be  seen  in  the  following  table : 


Wood 

Hickory 

Weight 
per  cubic  ft. 
in  Ibs. 

C-? 

Tensile 
Strength 
Ibs.  per  sq.  in. 

12  OOO 

Compressive 
Strength 
Ibs.  per  sq.  in. 

8,^OO 

Oak 

CQ 

12  OOO 

Q.OOO 

Ash 

..^8 

1  2.  OOO 

;/»*•"" 

6,000 

CONSTRUCTION   AND    OPERATION 


35 


Walnut , 38 

Spruce    25 

Pine    25 


8,000 
8,000 
5,000 


6,000 
5,000 
4,500 


Considering  the  marked  saving  in  weight  spruce  has 
a  greater  percentage  of  tensile  strength  than  any  of  the 
other  woods.  It  is  also  easier  to  find  in  long,  straight- 
grained  pieces  free  from  knots,  and  it  is  this  kind  only 
that  should  be  used  in  flying  machine  construction. 


One    Method    of   Wiring   Frame. 

You  will  next  need  some  spools  or  hanks  of  No.  6 
linen  shoe  thread,  metal  sockets,  a  supply  of  strong 
piano  wire,  a  quantity  of  closely-woven  silk  or  cotton- 
cloth,  glue,  turnbuckles,  varnish,  etc. 

Names  of  the  Various  Parts. 

The  long  strips,  four  in  number,  which  form  the  front 
and  rear  edges  of  the  upper  and  lower  frames,  are  called 
the  horizontal  beams.  These  are  each  20  feet  in  length. 
These  horizontal  beams  are  connected  by  upright  strips, 


36  FLYING    MACHINES: 

4  feet  long,  called  stanchions.  There  are  usually  12  of 
these,  six  on  the  front  edge,  and  six  on  the  rear.  They 
serve  to  hold  the  upper  plane  away  from  the  lower  one. 
Next  comes  the  ribs.  These  are  4  feet  in  length  (pro- 
jecting for  a  foot  over  the  rear  beam),  and  while  in- 
tended principally  as  a  support  to  the  cloth  covering  of 
the  planes,  also  tend  to  hold  the  frame  together  in  a 
horizontal  position  just  as  the  stanchions  do  in  the  ver- 
tical. There  are  forty-one  of  these  ribs,  twenty-one  on 
the  upper  and  twenty  on  the  lower  plane.  Then  come 
the  struts,  the  main  pieces  which  join  the  horizontal 
beams.  All  of  these  parts  are  shown  in  the  illustra- 
tions, reference  to  which  will  make  the  meaning  of  the 
various  names  clear. 

Quantity  and  Cost  of  Material. 

For  the  horizontal  beams  four  pieces  of  spruce,  20  feet 
long,  \y2  inches  wide  and  ^J  inch  thick  are  necessary. 
These  pieces  must  be  straight-grain,  and  absolutely  free 
from  knots.  If  it  is  impossible  to  obtain  clear  pieces 
of  this  length,  shorter  ones  may  be  spliced,  but  this  is 
not  advised  as  it  adds  materially  to  the  weight.  The 
twelve  stanchions  should  be  4  feet  long  and  j£  inch  in 
diameter  and  rounded  in  form  so  as  to  offer  as  little 
resistance  as  possible  to  the  wind.  The  struts,  there 
are  twelve  of  them,  are  3  feet  long  by  i^x^  inch.  For 
a  2O-foot  biplane  about  20  yards  of  stout  silk  or  un- 
bleached muslin,  of  standard  one  yard  width,  will  be 
needed.  The  forty-one  ribs  are  each  4  feet  long,  and 
y2  inch  square.  A  roll  of  No.  12  piano  wire,  twenty-four 
sockets,  a  package  of  small  copper  tacks,  a  pot  of  glue, 
and  similar  accessories  will  be  required.  The  entire 
cost  of  this  material  should  not  exceed  $20.  The  wood 
and  cloth  will  be  the  two  largest  items,  and  these  should 
not  cost  more  than  $10.  This  leaves  $10  for  the  varnish, 


CONSTRUCTION   AND    OPERATION  37 

wire,  tacks,  glue,  and  other  incidentals.  This  estimate 
is  made  for  cost  of  materials  only,  it  being  taken  for 
granted  that  the  experimenter  will  construct  his  own 
glider.  Should  the  services  of  a  carpenter  be  required 
the  total  cost  will  probably  approximate  $60  or  $70. 

Application   of   the   Rudders. 

The  figures  given  also  include  the  expense  of  rudders, 
but  the  details  of  these  have  not  been  included  as  the 
glider  is  really  complete  without  them.  Some  of  the  best 
flights  the  writer  ever  saw  were  made  by  Mr.  A.  M. 


20  FEET 


4fc2  FT 

Hh   FT 

2  rr 

Mfe   FT 

f  '/I  FT 

a  •»  «<  5 

Framework  of  Glider  With  Struts  in  Place. 


Framework  of  Glider  With  Ribs  in  Place. 


Herring  in  a  glider  without  a  rudder,  and  yet  there  can 
be  no  doubt  that  a  rudder,  properly  proportioned  and 
placed,  especially  a  rear  rudder,  is  of  great  value  to  the 
aviator  as  it  keeps  the  machine  with  its  head  to  the 
wind,  which  is  the  only  safe  position  for  a  novice.  For 
initial  educational  purposes,  however,  a  rudder  is  not 


38  FLYING   MACHINES: 

essential  as  the  glides  will,  or  should,  be  made  on  level 
ground,  in  moderate,  steady  wind  currents,  and  at  a 
modest  elevation.  The  addition  of  a  rudder,  therefore, 
may  well  be  left  until  the  aviator  has  become  reasonably 
expert  in  the  management  of  his  machine. 

Putting  the  Machine  Together. 

Having  obtained  the  necessary  material,  the  first  move 
is  to  have  the  rib  pieces  steamed  and  curved.  This  curve 
may  be  slight,  about  2  inches  for  the  4  feet.  AYhile 
this  is  being  done  the  other  parts  should  be  carefully 
rounded  so  the  square  edges  will  be  taken  off.  This 
may  be  done  with  sand  paper.  Next  apply  a  coat  of 
shellac,  and  when  dry  rub  it  down  thoroughly  with  fine 
sand  paper.  When  the  ribs  are  curved  treat  them  in 
the  same  way. 

Lay  two  of  the  long  horizontal  frame  pieces  on  the 
floor  3  feet  apart.  Between  these  place  six  of  the  strut 
pieces.  Put  one  at  each  end,  and  each  4^  feet  put 
another,  leaving  a  2-foot  space  in  the  center.  This  will 
give  you  four  struts  4T/<  feet  apart,  and  two  in  the  center 
2  feet  apart,  as  shown  in  the  illustration.  This  makes 
five  rectangles.  Be  sure  that  the  points  of  contact  are 
perfect,  and  that  the  struts  are  exactly  at  right  angles 
with  the  horizontal  frames.  This  is  a  most  important 
feature  because  if  your  frame  "skews"  or  twists  you 
cannot  keep  it  straight  in  the  air.  Now  glue  the  ends 
of  the  struts  to  the  frame  pieces,  using  plenty  of  glue, 
and  nail  on  strips  that  will  hold  the  frame  in  place  while 
the  glue  is  drying.  The  next  day  lash  the  joints  together 
firmly  with  the  shoe  thread,  winding  it  as  you  would  to 
mend  a  broken  gun  stock,  and  over  each  layer  put  a 
coating  of  glue.  This  done,  the  other  frame  pieces  and 
struts  may  be  treated  in  the  same  way,  and  you  will  thus 
get  the  foundations  for  the  two  planes. 


CONSTRUCTION   AND    OPERATION  39 

Another   Way  of   Placing   Struts. 

In  the  machines  built  for  professional  use  a  stronger 
and  more  certain  form  of  construction  is  desired.  This 
is  secured  by  the  placing  the  struts  for  the  lower  plane 
under  the  frame  piece,  and  those  for  the  upper  plane 
over  it,  allowing  them  in  each  instance  to  come  out  flush 
with  the  outer  edges  of  the  frame  pieces.  They  are  then 
securely  fastened  with  a  tie  plate  or  clamp  which  passes 
over  the  end  of  the  strut  and  is  bound  firmly  against 
the  surface  of  the  frame  piece  by  the  eye  bolts  of  the 
stanchion  sockets. 

Placing   the    Rib    Pieces. 

Take  one  of  the  frames  and  place  on  it  the  ribs,  with 
the  arched  side  up,  letting  one  end  of  the  ribs  come 


Various  Methods  of  Attaching  Stanchions  and  Guy  Wires. 

flush  with  the  front  edge  of  the  forward  frame,  and  the 
other  end  projecting  about  a  foot  beyond  the  rear  frame. 
The  manner  of  fastening  the  ribs  to  the  frame  pieces  is 
optional.  In  some  cases  they  are  lashed  with  shoe 
thread,  and  in  others  clamped  with  a  metal  clamp  fast- 
ened with  i^-inch  wood  screws.  Where  clamps  and 
screws  are  used  care  should  be  taken  to  make  slight 
holes  in  the  wood  with  an  awl  before  starting  the  screws 
so  as  to  lessen  any  tendency  to  split  the  wood.  On  the 
top  frame,  twenty-one  ribs  placed  one  foot  apart  will  be 


40  FLYING   MACHINES: 

required.     On  the  lower  frame,  because  of  the  opening 
left  for  the  operator's  body,  you  will  need  only  twenty. 

Joining  the  Two  Frames. 

The  two  frames  must  now  be  joined  together.  For  this 
you  will  need  twenty-four  aluminum  or  iron  sockets 
which  may  be  purchased  at  a  foundry  or  hardware  shop. 
These  sockets,  as  the  name  implies,  provide  a  receptacle 
in  which  the  end  of  a  stanchion  is  firmly  held,  and  have 
flanges  with  holes  for  eye-bolts  wrhich  hold  them  firmly 
to  the  frame  pieces,  and  also  serve  to  hold  the  guy  wires. 
In  addition  to  these  eye-bolt  holes  there  are  two  others 
through  which  screws  are  fastened  into  the  frame  pieces. 
On  the  front  frame  piece  of  the  bottom  plane  place  six 
sockets,  beginning  at  the  end  of  the  frame,  and  locating 
them  exactly  opposite  the  struts.  Screw  the  sockets  into 
position  with  wood  screws,  and  then  put  the  eye-bolts  in 
place.  Repeat  the  operation  on  the  rear  frame.  Xext 
put  the  sockets  for  the  upper  plane  frame  in  place. 

You  are  now  ready  to  bring  the  two  planes  together. 
Begin  by  inserting  the  stanchions  in  the  sockets  in  the 
lower  plane.  The  ends  may  need  a  little  rubbing  with 
sandpaper  to  get  them  into  the  sockets,  but  care  must 
be  taken  to  have  them  fit  snugly.  When  all  the  stan- 
chions are  in  place  on  the  lower  plane,  lift  the  upper 
plane  into  position,  and  fit  the  sockets  over  the  upper 
ends  of  the  stanchions. 

Trussing  with  Guy  Wires. 

The  next  move  is  to  "tie"  the  frame  together  rigidly 
by  the  aid  of  guy  wires.  This  is  where  the  No.  12  piano 
wire  comes  in.  Each  rectangle  formed  by  the  struts  and 
stanchions  with  the  exception  of  the  small  center  one, 
is  to  be  wired  separately  as  shown  in  the  illustration. 
At  each  of  the  eight  corners  forming  the  rectangle  the 


CONSTRUCTION   AND    OPERATION 


41 


ring  of  one  of  the  eye-bolts  will  be  found.  There  are 
two  ways  of  doing  this  "tieing,"  or  trussing.  One  is  to 
run  the  wires  diagonally  from  eye-bolt  to  eye-bolt,  de- 
pending upon  main  strength  to  pull  them  taut  enough, 
and  then  twist  the  ends  so  as  to  hold.  The  other  is  to 
first  make  a  loop  of  wire  at  each  eye-bolt,  and  connect 


Or  HUT 


Upper  Cut  Shows  Warping  Wires.     Lower  Cut  Shows  Method 
of  Fastening  Guy  Wires. 


these  loops  to  the  main  wires  with  turn-buckles.  This 
latter  method  is  the  best,  as  it  admits  of  the  tension  being 
regulated  by  simply  turning  the  buckle  so  as  to  draw 
the  ends  of  the  wire  closer  together.  A  glance  at  the 
illustration  will  make  this  plain,  and  also  show  how  the 
wires  are  to  be  placed.  The  proper  degree  of  tension 
may  be  determined  in  the  following  manner: 

After  the  frame  is  wired  place  each  end  on  a  saw-horse 
so   as   to   lift   the   entire   frame   clear   of   the   work-shop 


42  FLYING   MACHINES: 

floor.  Get  under  it,  in  the  center  rectangle  and,  grasping 
the  center  struts,  one  in  each  hand,  put  your  entire 
weight  on  the  structure.  'If  it  is  properly  put  together 
it  will  remain  rigid  and  unyielding.  Should  it  sag  ever 
so  slightly  the  tension  of  the  wires  must  be  increased 
until  any  tendency  to  sag,  no  matter  how  slight  it  may 
be,  is  overcome. 

Putting  on  the  Cloth. 

We  are  now  ready  to  put  on  the  cloth  covering  which 
holds  the  air  and  makes  the  machine  buoyant.  The  kind 
of  material  employed  is  of  small  account  so  long  as  it  is 
light,  strong,  and  wind-proof,  or  nearly  so.  Some  avi- 
ators use.  what  is  called  rubberized  silk,  others  prefer 
balloon  cloth.  Ordinary  muslin  of  good  quality,  treated 
with  a  coat  of  light  varnish  after  it  is  in  place,  will  an- 
swer all  the  purposes  of  the  amateur. 

Cut  the  cloth  into  strips  a  little  over  4  feet  in  length. 
As  you  have  20  feet  in  width  to  cover,  and  the  cloth  is 
one  yard  wide,  you  will  need  seven  strips  for  each  plane, 
so  as  to  allow  for  laps,  etc.  This  will  give  you  fourteen 
strips.  Glue  the  end  of  each  strip  around  the  front  hor- 
izontal beams  of  the  planes,  and  draw  each  strip  back, 
over  the  ribs,  tacking  the  edges  to  the  ribs  as  you  go 
along,  with  small  copper  or  brass  tacks.  In  doing  this 
keep  the  cloth  smooth  and  stretched  tight.  Tacks  should 
also  be  used  in  addition  to  the  glue,  to  hold  the  cloth  to 
the  horizontal  beams. 

Next,  give  the  cloth  a  coat  of  varnish  on  the  clear,  or 
upper  side,  and  when  this  is  dry  your  glider  will  be 
ready  for  use. 

Reinforcing  the  Cloth. 

While  not  absolutely  necessary  for  amateur  purposes, 
reinforcement  of  the  cloth,  so  as  to  avoid  any  tendency 
to  split  or  tear  out  from  wind-pressure,  is  desirable.  One 


CONSTRUCTION  AND    OPERATION 


43 


44  FLYING   MACHINES: 

way  of  doing  this  is  to  tack  narrow  strips  of  some 
heavier  material,  like  felt,  over  the  cloth  where  it  laps 
on  the  ribs.  Another  is  to  sew  slips  or  pockets  in  the 
cloth  itself  and  let  the  ribs  run  through  them.  Still  an- 
other method  is  to  sew  2-inch  strips  (of  the  same  ma- 
terial as  the  cover)  on  the  cloth,  placing  them  about  one 
yard  apart,  but  having  them  come  in  the  center  of  each 
piece  of  covering,  and  not  on  the  laps  where  the  various 
pieces  are  joined. 

Use  of  Armpieces. 

Should  armpieces  be  desired,  aside  from  those  afforded 
by  the  center  struts,  take  two  pieces  of  spruce,  3  feet 
long,  by  ixi^4  inches,  and  bolt  them  to  the  front  and 
rear  beams  of  the  lower  plane  about  14  inches  apart. 
These  will  be  more  comfortable  than  using  the  struts, 
as  the  operator  will  not  have  to  spread  his  arms  so 
much.  In  using  the  struts  the  operator,  as  a  rule,  takes 
hold  of  them  with  his  hands,  while  with  the  armpieces, 
as  the  name  implies,  he  places  his  arms  over  them,  one 
of  the  strips  coming  under  each  armpit. 

Frequently  somebody  asks  why  the  ribs  should  be 
curved.  The  answer  is  easy.  The  curvature  tends  to 
direct  the  air  downward  toward  the  rear  and,  as  the  air 
is  thus  forced  downward,  there  is  more  or  less  of  an  im- 
pact which  assists  in  propelling  the  aeroplane  upwards. 


CONSTRUCTION   AND    OPERATION 


45 


bfl 

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46 


FLYING   MACHINES: 


CHAPTER  VI. 


LEARNING  TO  FLY. 

Don't  be  too  ambitious  at  the  start.  Go  slow,  and 
avoid  unnecessary  risks.  At  its  best  there  is  an  element 
of  danger  in  aviation  which  cannot  be  entirely  elimi- 


All  Ready  for  a  Glide. 

nated,  but  it  may  be  greatly  reduced  and  minimized  by 
the  use  of  common  sense. 

Theoretically,  the  proper  way  to  begin  a  glide  is  from 
the  top  of  an  incline,  facing  against  the  wind,  so  that 

47 


48  FLYING   MACHINES: 

the  machine  will  soar  until  the  attraction  of  gravitation 
draws  it  gradually  to  the  ground.  This  is  the  manner  in 
which  experienced  aviators  operate,  but  it  must  be  kept 
in  mind  that  these  men  are  experts.  They  understand 
air  currents,  know  how  to  control  the  action  and  direc- 
tion of  their  machines  by  shifting  the  position  of  their 
bodies,  and  by  so  doing  avoid  accidents  which  would  be 
unavoidable  by  a  novice. 

Begin  on  Level  Ground. 

Make  your  first  flights  on  level  ground,  having  a  cou- 
ple of  men  to  assist  you  in  getting  the  apparatus  under 
headway.  Take  your  position  in  the  center  rectangle, 
back  far  enough  to  give  the  forward  edges  of  the  glider 
an  inclination  to  tilt  upward  very  slightly.  Now  start 
and  run  forward  at  a  moderately  rapid  gait,  one  man  at 
each  end  of  the  glider  assisting  you.  As  the  glider  cuts 
into  the  air  the  wind  will  catch  under  the  uplifted  edges 
of  the  curved  planes,  and  buoy  it  up  so  that  it  will  rise 
in  the  air  and  take  you  with  it.  This  rise  will  not  be 
great,  just  enough  to  keep  you  well  clear'  of  the  ground. 
Now  project  your  legs  a  little  to  the  front  so  as  to  shift 
the  center  of  gravity  a  trifle  and  bring  the  edges  of  the 
glider  on  an  exact  level  with  the  atmosphere.  This,  with 
the  momentum  acquired  in  the  start,  will  keep  the  ma- 
chine moving  forward  for  some  distance. 

Effect  of  Body  Movements. 

When  the  weight  of  the  body  is  slightly  back  of  the 
center  of  gravity  the  edges  of  the  advancing  planes  are 
tilted  slightly  upward.  The  glider  in  this  position  acts 
as  a  scoop,  taking  in  the  air  which,  in  turn,  lifts  it  off  the 
ground.  When  a  certain  altitude  is  reached — this  varies 
with  the  force  of  the  wind — the  tendency  to  a  forward 
movement  is  lost  and  the  glider  comes  to  the  ground. 


CONSTRUCTION   AND    OPERATION  49 

It  is  to  prolong  the  forward  movement  as  much  as  pos- 
sible that  the  operator  shifts  the  center  of  gravity  slight- 
ly, bringing  the  apparatus  on  an  even  keel  as  it  were  by 
lowering  the  advancing  edges.  This  done,  so  long  as 
there  is  momentum  enough  to  keep  the  glider  moving,  it 
will  remain  afloat. 

If  you  shift  your  body  well  forward  it  will  bring  the 
front  edges  of  the  glider  down,  and  elevate  the  rear  ones. 


Biplane  in  Flight  on  Even  Keel. 

In  this  way  the  air  will  be  "spilled"  out  at  the  rear,  and, 
having  lost  the  air  support  or  buoyancy,  the  glider  comes 
down  to  the  ground.  A  few  flights  will  make  any  ordi- 
nary man  proficient  in  the  control  of  his  apparatus  by  his 
body  movements,  not  only  as  concerns  the  elevating  and 
depressing  of  the  advancing  edges,  but  also  actual  steer- 


50  FLYING   MACHINES: 

ing.  You  will  quickly  learn,  for  instance,  that,  as  the 
shifting  of  the  bodily  weight  backwards  and  forwards 
affects  the  upward  and  downward  trend  of  the  planes,  so 
a  movement  sideways — to  the  left  or  the  right — affects 
the  direction  in  which  the  glider  travels. 

Ascends   at  an  Angle. 

In  ascending,  the  glider  and  flying  machine,  like  the 
bird,  makes  an  angular,  not  a  vertical  flight.  Just  what 
this  angle  of  ascension  may  be  is  difficult  to  determine. 
It  is  probable  and  in  fact  altogether  likely,  that  it  varies 
with  the  force  of  the  wind,  weight  of  the  rising  body, 
power  of  propulsion,  etc.  This,  in  the  language  of  phys- 
icists, is  the  angle  of  inclination,  and,  as  a  general  thing, 
under  normal  conditions  (still  air)  should  be  put  down  as 
about  one  in  ten,  or  5^4  degrees.  This  would  be  an  ideal 
condition,  but  it  has  not,  as  yet  been  reached.  The  force 
of  the  wind  affects  the  angle  considerably,  as  does  also 
the  weight  and  velocity  of  the  apparatus.  In  general 
practice  the  angle  varies  from  23  to  45  degrees.  At 
more  than  45  degrees  the  supporting  effort  is  overcome 
by  the  resistance  to  forward  motion. 

Increasing  the  speed  or  propulsive  force,  tends  to 
lessen  the  angle  at  which  the  machine  may  be  success- 
full}'-  operated  because  it  reduces  the  wind  pressure. 
Most  of  the  modern  flying  machines  are  operated  at  an 
angle  of  23  degrees,  or  less. 

Maintaining  an  Equilibrium. 

Stable  equilibrium  is  one  of  the  main  essentials  to 
successful  flight,  and  this  cannot  be  preserved  in  an 
uncertain,  gusty  wind,  especially  by  an  amateur.  The 
novice  should  not  attempt  a  glide  unless  the  conditions 
are  just  right.  These  conditions  are :  A  clear,  level 
space,  without  obstructions,  such  as  trees,  etc.,  and  a 


CONSTRUCTION   AND    OPERATION  51 

steady  wind  of  not  exceeding  twelve  miles  an  hour.    Al- 
ways fly  against  the  wind. 

When  a  reasonable  amount  of  proficiency  in  the  han- 
dling of  the  machine  on  level  ground  has  been  acquired 
the  field  of  practice  may  be  changed  to  some  gentle 
slope.  In  starting  from  a  slope  it  will  be  found  easier 


From    Scientific    American    Supplement. 

Glider   Struck  by  a  Side  Gust. 

Note  how  operator  seeks   to  restore  equilibrium  by  shifting  his 
weight   toward   uplifted   end. 

to  keep  the  machine  afloat,  but  the  experience  at  first  is 
likely  to  be  very  disconcerting  to  a  man  of  less  than  iron 
nerve.  As  the  glider  sails  away  from  the  top  of  the 
slope  the  distance  between  him  and  the  ground  increases 
rapidly  until  the  aviator  thinks  he  is  up  a  hundred  miles 
in  the  air.  If  he  will  keep  cool,  manipulate  his  apparatus 
so  as  to  preserve  its  equilibrium,  and  "let  nature  take  its 
course,"  he  will  come  down  gradually  and  safely  to  the 
ground  at  a  considerable  distance  from  the  starting  place. 


52 


FLYING   MACHINES: 


This  is  one  advantage  of  starting  from  an  elevation  — 
your  machine  will  go  further. 

But,  if  the  aviator  becomes  "rattled"  ;  if  he  loses  con- 
trol of  his  machine,  serious  results,  including  a  bad  fall 
with  risk  of  death,  are  almost  certain.  And  yet  this 
practice  is  just  as  necessary  as  the  initial  lessons  on 
level  ground.  When  judgment  is  used,  and  "haste  made 
slowly,"  there  is  very  little  real  danger.  While  experi- 


Action  of  the   Vertical   Rudder. 


menting  with  gliders  the  Wrights  made  flights  innumer- 
able under  all  sorts  of  conditions  and  never  had  an  acci- 
dent of  any  kind. 

Effects  of  Wind  Currents. 

The  larger  the  machine  the  more  difficult  it  will  be  to 
control  its  movements  in  the  air,  and  yet  enlargement  is 
absolutely  necessary  as  weight,  in  the  form  of  motor, 
rudder,  etc.,  is  added. 

Air  currents  near  the  surface  of  the  ground  are  di- 
verted by  every  obstruction  unless  the  wind  is  blowing 
hard  enough  to  remove  the  obstruction  entirely.  Take, 
for  instance,  the  case  of  a  tree  or  shrub,  in  a  moderate 
wind  of  from  ten  to  twelve  miles  an  hour.  As  the  wind 
strikes  the  tree  it  divides,  part  going  to  one  side  and 


CONSTRUCTION  AND   OPERATION 


53 


part  going  to  the  other,  while  still  another  part  is  direct- 
ed upward  and  goes  over  the  top  of  the  obstruction. 
This  makes  the  handling  of  a  glider  on  an  obstructed 
field  difficult  and  uncertain.  To  handle  a  glider  success- 
fully the  place  of  operation  should  be  clear  and  the  wind 
moderate  and  steady.  If  it  is  gusty  postpone  your  flight. 
In  this  connection  it  will  be  well  to  understand  the  veloc- 
ity of  the  wind,  and  what  it  means  as  shown  in  the 
following  table : 

Miles  per  hour  Feet  per  second  Pressure  per  sq.  foot 

10  14.7  492 

25  36.7  3.075 

50  73.3  12.300 

100  146.6  49.200 


Biplane    Glider   with    Operator's    Seat. 


Pressure  of  wind  increases  in  proportion  to  the  square 
of  the  velocity.  Thus  wind  at  10  miles  an  hour  has  four 
times  the  pressure  of  wind  at  5  miles  an  hour.  The 
greater  this  pressure  the  large  and  heavier  the  object 
which  can  be  raised.  Any  boy  who  has  had  experience 
in  flying  kites  can  testify  to  this.  High  winds,  however, 


54  FLYING   MACHINES: 

are  almost  invariably  gusty  and  uncertain  as  to  direc- 
tion, and  this  makes  them  dangerous  for  aviators.  It 
is  also  a  self-evident  fact  that,  beyond  a  certain  stage, 
the  harder  the  wind  blows  the  more  difficult  it  is  to 
make  headway  against  it. 

Launching   Device  for  Gliders. 

On  page  195  will  be  found  a  diagram  of  the  various 
parts  of  a  launcher  for  gliders,  designed  and  patented 
by  Mr.  Octave  Chanute.  In  describing  this  invention 
in  Aeronautics,  Mr.  Chanute  says: 

"In  practising,  the  track,  preferably  portable,  is  gen- 
erally laid  in  the  direction  of  the  existing  wind  and 
the  car,  preferably  a  light  platform-car,  is  placed  on  the 
track.  The  truck  carrying  the  winding-drum  and  its  mo- 
tor is  placed  to  windward  a  suitable  distance — say  from 
two  hundred  to  one  thousand  feet — and  is  firmly  blocked 
or  anchored  in  line  with  the  portable  track,  which  is 
preferably  80  or  100  feet  in  length.  The  flying  or  gliding 
machine  to  be  launched  with  its  operator  is  placed  on 
the  platform-car  at  the  leeward  end  of  the  portable  track. 
The  line,  which  is  preferably  a  flexible  combination 
wire-and-cord  cable,  is  stretched  between  the  winding- 
drum  on  the  track  and  detachably  secured  to  the  flying 
or  gliding  machine,  preferably  by  means  of  a  trip-hoop, 
or  else  held  in  the  hand  of  the  operator,  so  that  the 
operator  may  readily  detach  the  same  from  the  flying- 
machine  when  the  desired  height  is  attained. 

How  Glider  Is  Started. 

"Then  upon  a  signal  given  by  the  operator  the  en- 
gineer at  the  motor  puts  it  into  operation,  gradually  in- 
creasing the  speed  until  the  line  is  wound  upon  the  drum 
at  a  maximum  speed  of,  say,  thirty  miles  an  hour.  The 
operator  of  the  flying-machine,  whether  he  stands  up- 


CONSTRUCTION   AND    OPERATION  55 

right  and  carries  it  on  his  shoulders,  or  whether  he  sits 
or  lies  down  prone  upon  it,  adjusts  the  aeroplane  or 
carrying  surfaces  so  that  the  wind  shall  strike  them  on 
the  top  and  press  downward  instead  of  upward  until 
the  platform-car  under  action  of  the  winding-drum  and 
line  attains  the  required  speed. 

"When  the  operator  judges  that  his  speed  is  sufficient, 
and  this  depends  upon  the  velocity  of  the  wind  as  well 
as  that  of  the  car  moving  against  the  wind,  he  quickly 
causes  the  front  of  the  flying-machine  to  tip  upward,  so 
that  the  relative  wind  striking  on  the  under  side  of  the 
planes  or  carrying  surfaces  shall  lift  the  flying  machine 
into  the  air.  It  then  ascends  like  a  kite  to  such  height 
as  may  be  desired  by  the  operator,  who  then  trips  the 
hook  and  releases  the  line  from  the  machine. 

What  the  Operator  Does. 

"The  operator  being  now  free  in  the  air  has  a  certain 
initial  velocity  imparted  by  the  winding-drum  and  line 
and  also  a  potential  energy  corresponding  to  his  height 
above  the  ground.  If  the  flying  or  gliding  machine  is 
provided  with  a  motor,  he  can  utilize  that  in  his  further 
flight,  and  if  it  is  a  simple  gliding  machine  without 
motor  he  can  make  a  descending  flight  through  the  air 
to  such  distance  as  corresponds  to  the  velocity  acquired 
and  the  height  gained,  steering  meanwhile  by  the  de- 
vices provided  for  that  purpose. 

"The  simplest  operation  or  maneuver  is  to  continue 
the  flight  straight  ahead  against  the  wind ;  but  it  is  pos- 
sible to  vary  this  course  to  the  right  or  left,  or  even  to 
return  in  downward  flight  with  the  wind  to  the  vicinity 
of  the  starting-point.  Upon  nearing  the  ground  the 
operator  tips  upward  his  carrying-surfaces  and  stops  his 
headway  upon  the  cushion  of  increased  air  resistance 
so  caused.  The  operator  is  in  no  way  permanently 


66  FLYING  MACHINES: 

fastened  to  his  machine,  and  the  machine  and  the  oper- 
ator simply  rest  upon  the  light  platform-car,  so  that 
the  operator  is  free  to  rise  with  the  machine  from  the 
car  whenever  the  required  initial  velocity  is  attained. 

Motor  For  the  Launcher. 

"The  motor  may  be  of  any  suitable  kind  or  construc- 
tion, but  is  preferably  an  electric  or  gasolene  motor. 
The  winding-drum  is  furnished  with  any  suitable  or  cus- 
tomary reversing-guide  to  cause  the  line  to  wind  smoothly 
and  evenly  upon  the  drum.  The  line  is  preferably  a 
cable  composed  of  flexible  wire  and  having  a  cotton  or 
other  cord  core  to  increase  its  flexibility.  The  line  ex- 
tends from  the  drum  to  the  flying  or  gliding  machine. 
Its  free  end  may,  if  desired,  be  grasped  and  held  by  the 
operator  until  the  flying-machine  ascends  to  the  desired 
height,  when  by  simply  letting  go  of  the  line  the  operator 
may  continue  his  flight  free.  The  line,  however,  is  pref- 
erably connected  to  the  flying  or  gliding  machine 
directly  by  a  trip-hook  having  a  handle  or  trip  lever 
within  reach  of  the  operator,  so  that  when  he  ascends 
to  the  required  height  he  may  readily  detach  the  line 
from  the  flying  or  gliding  machine." 


CHAPTER  VII. 

PUTTING  ON  THE  RUDDER. 

Gliders  as  a  rule  have  only  one  rudder,  and  this  is  in 
the  rear.  It  tends  to  keep  the  apparatus  with  its  head  to 
the  wind.  Unlike  the  rudder  on  a  boat  it  is  fixed  and 
immovable.  The  real  motor-propelled  flying  machine, 
generally  has  both  front  and  rear  rudders  manipulated 
by  wire  cables  at  the  will  of  the  operator. 

Allowing  that  the  amateur  has  become  reasonably  ex- 
pert in  the  manipulation  of  the  glider  he  should,  before 
constructing  an  actual  flying  machine,  equip  his  glider 
with  a  rudder. 

Cross  Pieces  for  Rudder  Beam. 

To  do  this  he  should  begin  by  putting  in  a  cross  piece, 
2  feet  long  by  ij4x24  inches  between  the  center  struts, 
in  the  lower  plane.  This  may  be  fastened  to  the  struts 
with  bolts  or  braces.  The  former  method  is  preferable. 
On  this  cross  piece,  and  on  the  rear  frame  of  the  plane 
itself,  the  rudder  beam  is  clamped  and  bolted.  This 
rudder  beam  is  8  feet  n  inches  long.  Having  put  these 
in  place  duplicate  them  in  exactly  the  same  manner  and 
dimensions  from  the  upper  frame.  The  cross  pieces  on 
which  the  ends  of  the  rudder  beams  are  clamped  should 
be  placed  about  one  foot  in  advance  of  the  rear  frame 
beam. 

The  Rudder  Itself. 

The  next  step  is  to  construct  the  rudder  itself.     This 

57 


58  FLYING   MACHINES: 

consists  of  two  sections,  one  horizontal,  the  other  verti- 
cal. The  latter  keeps  the  aeroplane  headed  into  the  wind, 
while  the  former  keeps  it  steady — preserves  the  equili- 
brium. 

The  rudder  beams  form  the  top  and  bottom  frames  of 
the  vertical  rudder.  To  these  are  bolted  and  clamped 
two  upright  pieces,  3  feet,  10  inches  in  length,  and  y^ 
inch  in  cross  section.  These  latter  pieces  are  placed  about 
two  feet  apart.  This  completes  the  framework  of  the 
vertical  rudder.  See  next  page  (59). 

For  the  horizontal  rudder  you  will  require  two  strips 
6  feet  long,  and  four  2  feet  long.  Find  the  exact  center 
of  the  upright  pieces  on  the  vertical  rudder,  and  at  this 
spot  fasten  with  bolts  the  long  pieces  of  the  horizontal, 
placing  them  on  the  outside  of  the  vertical  strips.  Next 
join  the  ends  of  the  horizontal  strips  with  the  2-foot 
pieces,  using  small  screws  and  corner  braces.  This  done 
you  will  have  two  of  the  2-foot  pieces  left.  These  go  in 
the  center  of  the  horizontal  frame,  "straddling"  the  ver- 
tical strips,  as  shown  in  the  illustration. 

The  framework  is  to  be  covered  with  cloth  in  the 
same  manner  as  the  planes.  For  this  about  ten  yards 
will  be  needed. 

Strengthening  the  Rudder. 

To  ensure  rigidity  the  rudder  must  be  stayed  with 
guy  wires.  For  this  purpose  the  No.  12  piano  wire  is 
the  best.  Begin  by  running  two  of  these  wires  from  the 
top  eye-bolts  of  stanchions  3  and  4,  page  37,  to  rudder 
beam  where  it  joins  the  rudder  planes,  fastening  them 
at  the  bottom.  Then  run  two  wires  from  the  top  of  the 
rudder  beam  at  the  same  point,  to  the  bottom  eye-bolts 
of  the  same  stanchions.  This  will  give  you  four  diag- 
onal wires  reaching  from  the  rudder  beam  to  the  top 
and  bottom  planes  of  the  glider.  Now,  from  the  outer 


CONSTRUCTION  AND    OPERATION  59 

ends  of  the  rudder  frame  run  four  similar  diagonal  wires 
to  the  end  of  the  rudder  beam  where  it  rests  on  the 
cross  piece.  You  will  then  have  eight  truss  wires 
strengthening  the  connection  of  the  rudder  to  the  main 
body  of  the  glider. 

The  framework  of  the  rudder  planes  is  then  to  be 
braced  in  the  same  way,  which  will  take  eight  more 
wires,  four  for  each  rudder  plane.  All  the  wires  are 
to  be  connected  at  one  end  with  turn-buckles  so  the 
tension  may  be  regulated  as  desired. 

In  forming  the  rudder  frame  it  will  be  well  to  mortise 
the  corners,  tack  them  together  with  small  nails,  and 
then  put  in  a  corner  brace  in  the  inside  of  each  joint. 
In  doing  this  bear  in  mind  that  the  material  to  be  thus 
fastened  is  light,  and  consequently  the  lightest  of  nails, 
screws,  bolts  and  corner  pieces,  etc.,  is  necessary. 


Framework  of  Rudder  for  Glider. 


60 


FLYING   MACHINES: 


CHAPTER  VIII. 


THE  REAL  FLYING  MACHINE. 

We  will  now  assume  that  you  have  become  proficient 
enough  to  warrant  an  attempt  at  the  construction  of  a 
real  flying  machine — one  that  will  not  only  remain  sus- 
pended in  the  air  at  the  will  of  the  operator,  but  make 
respectable  progress  in  whatever  direction  he  may  de- 


General  Outline  of  Curtiss'  Main  Framework. 

sire  to  go.  The  glider,  it  must  be  remembered,  is  not 
steerable,  except  to  a  limited  extent,  and  moves  only  in 
one  direction — against  the  wind.  Besides  this  its  power 
of  flotation — suspension  in  the  air — is  circumscribed. 

Larger  Surface  Area  Required. 

The  real  flying  machine  is  the  glider  enlarged,  and 
equipped  with  motor  and  propeller.  The  first  thing  to 
do  is  to  decide  upon  the  size  required.  While  a  glider 

61 


62  FLYING   MACHINES: 

of  20  foot  spread  is  large  enough  to  sustain  a  man  it 
could  not  under  any  possible  conditions,  be  made  to  rise 
with  the  weight  of  the  motor,  propeller  and  similar 
equipment  added.  As  the  load  is  increased  so  must  the 
surface  area  of  the  planes  be  increased.  Just  what  "this 
increase  in  surface  area  should  be  is  problematical  as  ex- 
perienced aviators  disagree,  but  as  a  general  proposition 
it  may  be  placed  at  from  three  to  four  times  the  area  of 
a  2o-foot  glider. 

Some  Practical  Examples. 

The  Wrights  used  a  biplane  41  feet  in  spread,  and  6l/2 
ft.  deep.  This,  for  the  two  planes,  gives  a  total  surface 
area  of  538  square  feet,  inclusive  of  auxiliary  planes. 
This  sustains  the  engine  equipment,  operator,  etc.,  a  total 
weight  officially  announced  at  1,070  pounds.  It  shows 
a  lifting  capacity  of  about  two  pounds  to  the  square 
foot  of  plane  surface,  as  against  a  lifting  capacity  of 
about  YI  pound  per  square  foot  of  plane  surface  for  the 
2O-foot  glider.  This  same  Wright  machine  is  also  re- 
ported to  have  made  a  successful  flight,  carrying  a  total 
load  of  1,100  pounds,  which  would  be  over  two  pounds 
for  each  square  foot  of  surface  area,  which,  with  auxil- 
iary planes,  is  538  square  feet. 

To  attain  the  same  results  in  a  monoplane,  the  single 
surface  would  have  to  be  60  feet  in  spread  and  9  feet 
deep.  But,  while  this  is  the  mathematical  rule,  Bleriot 
has  demonstrated  that  it  does  not  always  hold  good. 
On  his  record-breaking  trip  across  the  English  chan- 
nel, July  25th,  1909,  the  Frenchman  was  carried  in  a 
monoplane  2.^/2  feet  in  spread,  and  with  a  total  sustain- 
ing surface  of  150^  square  feet.  The  total  weight  of 
the  outfit,  including  machine,  operator  and  fuel  suffi- 
cient for  a  three-hour  run,  was  only  660  pounds.  With 
an  engine  of  (nominally)  25  horsepower  the  distance  of 
21  miles  was  covered  in  37  minutes. 


CONSTRUCTION   AND    OPERATION  63 

Which  is  the  Best? 

Right  here  an  established  mathematical  quantity  is 
involved.  A  small  plane  surface  offers  less  resistance 
to  the  air  than  a  large  one  and  consequently  can  attain 
a  higher  rate  of  speed.  As  explained  further  on  in  this 
chapter  speed  is  an  important  factor  in  the  matter  of 
weight-sustaining  capacity.  A  machine  that  travels  one- 
third  faster  than  another  can  get  along  with  one-half  the 


Framework  of  Bleriot  Monoplane. 

surface  area  of  the  latter  without  affecting  the  load.  See 
the  closing  paragraph  of  this  chapter  on  this  point.  In 
theory  the  construction  is  also  the  simplest,  but  this  is 
not  always  found  to  be  so  in  practice.  The  designing 
and  carrying  into  execution  of  plans  for  an  extensive 
area  like  that  of  a  monoplane  involves  great  skill  and 
cleverness  in  getting  a  framework  that  will  be  strong 
enough  to  furnish  the  requisite  support  without  an  undue 


64  FLYING   MACHINES: 

excess  of  weight.  This  proposition  is  greatly  simplified 
in  the  biplane  and,  while  the  speed  attained  by  the  latter 
may  not  be  quite  so  great  as  that  of  the  monoplane,  it 
has  much  larger  weight-carrying  capacity. 

Proper  Sizes  For  Frame. 

Allowing  that  the  biplane  form  is  selected  the  con- 
struction may  be  practically  identical  with  that  of  the 
2o-foot  glider  described  in  Chapter  V.,  except  as  to  size 
and  elimination  of  the  armpieces.  In  size  the  surface 
planes  should  be  about  twice  as  large  as  those  of  the 
2O-foot  glider,  viz :  40  feet  spread  instead  of  20,  and  6  feet 
deep  instead  of  3.  The  horizontal  beams,  struts,  stan- 
chions, ribs,  etc.,  should  also  be  increased  in  size  pro- 
portionately. 

While  care  in  the  selection  of  clear,  straight-grained 
timber  is  important  in  the  glider,  it  is  still  more  im- 
portant in  the  construction  of  a  motor-equipped  flying 
machine  as  the  strain  on  the  various  parts  will  be  much 
greater. 

How  to  Splice  Timbers. 

It  is  practically  certain  that  you  will  have  to  resort  to 
splicing  the  horizontal  beams  as  it  will  be  difficult,  if  not 
impossible,  to  find  4O-foot  pieces  of  timber  totally  free 
from  knots  and  worm  holes,  and  of  straight  grain. 

If  splicing  is  necessary  select  two  good  2O-foot  pieces, 
3  inches  wide  and  iV2  inches  thick,  and  one  lo-foot  long, 
of  the  same  thickness  and  width.  Plane  off  the  bottom 
sides  of  the  lo-foot  strip,  beginning  about  two  feet  back 
from  each  end,  and  taper  them  so  the  strip  will  be  about 
24  inch  thick  at  the  extreme  ends.  Lay  the  two  2ofoot 
beams  end  to  end,  and  under  the  joint  thus  made  place 
the  lo-foot  strip,  with  the  planed-off  ends  downward. 
The  joint  of  the  2O-foot  pieces  should  be  directly  in  the 
center  of  the  ic-foot  piece.  Bore  ten  holes  (with  a  y\- 


CONSTRUCTION   AND    OPERATION  65 

inch  augur)  equi-distant  apart  through  the  2o-foot 
strips  and  the  lo-foot  strip  under  them.  Through  these 
holes  run  ^[-inch  stove  bolts  with  round,  beveled  heads. 
In  placing  these  bolts  use  washers  top  and  bottom,  one 
between  the  head  and  the  top  beam,  and  the  other  be- 
tween the  bottom  beam  and  the  screw  nut  which  holds 
the  bolt.  Screw  the  nuts  down  hard  so  as  to  bring  the 
two  beams  tightly  together,  and  you  will  have  a  rigid 
4O-foot  beam. 

Splicing  with  Metal  Sleeves. 

An  even  better  way  of  making  a  splice  is  by  tonguing 
and  grooving  the  ends  of  the  frame  pieces  and  enclosing 


Splicing   Beam   With   Third   Piece. 


them  in  a  metal  sleeve,  but  it  requires  more  mechanical 
skill  than  the  method  first  named.  The  operation  of 
tonguing  and  grooving  is  especially  delicate  and  calls 
for  extreme  nicety  of  touch  in  the  handling  of  tools,  but 
if  this  dexerity  is  possessed  the  job  will  be  much  more 
satisfactory  than  one  done  with  a  third  timber. 

As  the  frame  pieces  are  generally  about  il/2  inch  in 
diameter,  the  tongue  and  the  groove  into  which  the 
tongue  fits  must  be  correspondingly  small.  Begin  by 
sawing  into  one  side  of  one  of  the  frame  pieces  about  4 
inches  back  from  the  end.  Make  the  cut  about  */2  inch 
deep.  Then  turn  the  piece  over  and  duplicate  the  cut. 
Next  saw  down  from  the  end  to  these  cuts.  When  the 


06  FLYING   MACHINES: 

sawed-out  parts  are  removed  you  will  have  a  "tongue" 
in  the  end  of  the  frame  timber  4  inches  long  and  l/2  inch 
thick.  The  next  move  is  to  saw  out  a  ^-inch  groove  in 
the  end  of  the  frame  piece  which  is  to  be  joined.  You 
will  have  to  use  a  small  chisel  to  remove  the  ^6-inch  bit. 
This  will  leave  a  groove  into  which  the  tongue  will  fit 
easily. 

Joining  the  Two  Pieces. 

Take  a  thin  metal  sleeve — this  is  merely  a  hollow  tube 
of  aluminum  or  brass  open  at  each  end — 8  inches  long, 
and  slip  it  over  either  the  tongued  or  grooved  end  of  one 
of  the  frame  timbers.  It  is  well  to  have  the  sleeve  fit 


Splicing    Beam    With    Metal    Sleeve. 


snugly,  and  this  may  necessitate  a  sand-papering  of  the 
frame  pieces  so  the  sleeve  will  slip  on. 

Push  the  sleeve  well  back  out  of  the  way.  Cover  the 
tongue  thoroughly  with  glue,  and  also  put  some  on  the 
inside  of  the  groove.  Use  plenty  of  glue.  Now  press 
the  tongue  into  the  groove,  and  keep  the  ends  firmly  to- 
gether until  the  glue  is  thoroughly  dried.  Rub  off  the 
joint  lightly  with  sand-paper  to  remove  any  of  the  glue 
which  may  have  oozed  out,  and  slip  the  sleeve  into  place 
over  the  joint.  Tack  the  sleeve  in  position  with  small 
copper  tacks,  and  you  will  have  an  ideal  splice. 


CONSTRUCTION  AND   OPERATION  67 

The  same  operation  is  to  be  repeated  on  each  of  the 
four  frame  pieces.  Two  2O-foot  pieces  joined  in  this 
way  will  give  a  substantial  frame,  but  when  suitable 
timber  of  this  kind  can  not  be  had,  three  pieces,  each  6 
feet  ii  inches  long,  may  be  used.  This  would  give  20 
feet  9  inches,  of  which  8  inches  will  be  taken  up  in  the 
two  joints,  leaving  the  frame  20  feet  I  inch  long. 


Bicycle  Spoke  and  Nipple  for  Tightening  Guy  Wires. 


t 

^COTTON  cov««a& 

.UB6ER,   Oet-B 
ft*  ft"* 

At  Left,  Substitute  for  Turnbuckle.    At  Right,  Bleriot's  Shock 

Absorber. 


68  FLYING   MACHINES: 

Installation   of   Motor. 

Next  comes  the  installation  of  the  motor.  The  kinds 
and  efficiency  of  the  various  types  are  described  in  the 
following  chapter  (IX).  All  we  are  interested  in  at 
this  point  is  the  manner  of  installation.  This  varies 
according  to  the  personal  ideas  of  the  aviator.  Thus  one 
man  puts  his  motor  in  the  front  of  his  machine,  another 
places  it  in  the  center,  and  still  another  finds  the  rear  of 
the  frame  the  best.  All  get  good  results,  the  comparative 
advantages  of  which  it  is  difficult  to  estimate.  Where 
one  man,  as  already  explained,  flies  faster  than  another, 
the  one  beaten  from  the  speed  standpoint  has  an  advan- 
tage in  the  matter  of  carrying  weight,  etc. 

The  ideas  of  various  well-known  aviators  as  to  the 
correct  placing  of  motors  may  be  had  from  the  following : 

Wrights — In  rear  of  machine  and  to  one  side. 

Curtiss — Well  to  rear,  about  midway  between  upper 
and  lower  planes. 

Raich — In  rear,  above  the  center. 

Brauner-Smith — In  exact  center  of  machine. 

Van  Anden — In  center. 

Herring-Burgess — Directly   behind    operator. 

Voisin — In  rear,  and  on  lower  plane. 

Bleriot — In  front. 

R.  E.  P.— In  front. 

The  One  Chief  Object. 

An  even  distribution  of  the  load  so  as  to  assist  in 
maintaining  the  equilibrium  of  the  machine,  should  be 
the  one  chief  object  in  deciding  upon  the  location  of  the 
motor.  It  matters  little  what  particular  spot  is  selected 
so  long  as  the  weight  does  not  tend  to  overbalance  the 
machine,  or  to  "throw  it  off  an  even  keel/'  It  is  just 
like  loading  a  vessel,  an  operation  in  which  the  expert 


CONSTRUCTION  AND   OPERATION 


69 


seeks  to  so  distribute  the  weight  of  the  cargo  as  to  keep 
the  vessel  in  a  perfectly  upright  position,  and  prevent  a 
"list"  or  leaning  to  one  side.  The  more  evenly  the  cargo 
is  distributed  the  more  perfect  will  be  the  equilibrium  of 


70  FLYING  MACHINES: 

the  vessel  and  the  better  it  can  be  handled.  Sometimes, 
when  not  properly  stowed,  the  cargo  shifts,  and  this  at 
once  affects  the  position  of  the  craft.  When  a  ship 
"lists"  to  starboard  or  port  a  preponderating  weight  of 
the  cargo  has  shifted  sideways ;  if  bow  or  stern  is  unduly 
depressed  it  is  a  sure  indication  that  the  cargo  has  shifted 
accordingly.  In  either  event  the  handling  of  the  craft 
becomes  not  only  difficult,  but  extremely  hazardous. 
Exactly  the  same  conditions  prevail  in  the  handling  of  a 
flying  machine. 

Shape  of  Machine  a  Factor. 

In  placing  the  motor  you  must  be  governed  largely  by 
the  shape  and  construction  of  the  flying  machine  frame. 
If  the  bulk  of  the  weight  of  the  machine  and  auxiliaries 
is  toward  the  rear,  then  the  natural  location  for  the  mo- 
tor will  be  well  to  the  front  so  as  to  counterbalance  the 
excess  in  rear  weight.  In  the  same  way  if  the  pre- 
ponderance of  the  weight  is  forward,  then  the  motor 
should  be  placed  back  of  the  center. 

As  the  propeller  blade  is  really  an  integral  part  of  the 
motor,  the  latter  being  useless  without  it,  its  placing 
naturally  depends  upon  the  location  selected  for  the 
motor. 

Rudders  and  Auxiliary  Planes. 

Here  again  there  is  great  diversity  of  opinion  among 
aviators  as  to  size,  location  and  form.  The  striking 
difference  of  ideas  in  this  respect  is  well  illustrated  in 
the  choice  made  by  prominent  makers  as  follows: 

Voisin — horizontal  rudder,  with  two  wing-like  planes, 
in  front;  box-like  longitudinal  stability  plane  in  rear, 
inside  of  which  is  a  vertical  rudder. 

Wright — large  biplane  horizontal  rudder  in  front  at 
considerable  distance — about  10  feet — from  the  main 
planes;  vertical  biplane  rudder  in  rear;  ends  of  upper 


CONSTRUCTION   AND    OPERATION 


71 


and   lower  main   planes   made   flexible   so   they   may  be 
moved. 

Curtiss — horizontal  biplane  rudder,  with  vertical  damp- 
ing plane  between  the  rudder  planes  about  10  feet  in 
front  of  main  planes ;  vertical  rudder  in  rear ;  stabilizing 
planes  at  each  end  of  upper  main  plane. 


AAKTAt- 


Strut    Connection,   Wire   Fastening,   Etc.,   on   Van   Anden. 

Bleriot — V-shaped  stabilizing  fin,  proj-ecting  from  rear 
of  plane,  with  broad  end  outward;  to  the  broad  end  of 
this  fin  is  hinged  a  vertical  rudder;  horizontal  biplane 
rudder,  also  in  rear,  under  the  fin. 

These  instances  show  forcefully  the  wide  diversity  of 
opinion  existing  among  experienced  aviators  as  to  the 
best  manner  of  placing  the  rudders  and  stabilizing,  or 


72  FLYING   MACHINES: 

auxiliary  planes,  and  make  manifest  how  hopeless  would 
be  the  task  of  attempting  to  select  any  one  form  and 
advise  its  exclusive  use. 

Rudder  and  Auxiliary  Construction. 

The  material  used  in  the  construction  of  the  rudders 
and  auxiliary  planes  is  the  same  as  that  used  in  the  main 
planes — spruce  for  the  framework  and  some  kind  of 
rubberized  or  varnished  cloth  for  the  covering.  The 
frames  are  joined  and  wired  in  exactly  the  same  manner 
as  the  frames  of  the  main  planes,  the  purpose  being  to 
secure  the  same  strength  and  rigidity.  Dimensions  of 
the  various  parts  depend  upon  the  plan  adopted  and  the 
size  of  the  main  plane. 

No  details  as  to  exact  dimensions  of  these  rudders  and 
auxiliary  planes  are  obtainable.  The  various  builders, 
while  willing  enough  to  supply  data  as  to  the  general 
measurements,  weight,  power,  etc.,  of  their  machines, 
appear  to  have  overlooked  the  details  of  the  auxiliary 
parts,  thinking,  perhaps,  that  these  were  of  no  particular 
import  to  the  general  public.  In  the  Wright  machine,  the 
rear  horizontal  and  front  vertical  rudders  may  be  set 
doAvn  as  being  about  one-quarter  (probably  a  little  less) 
the  size  of  the  main  supporting  planes. 

Arrangement  of  Alighting  Gear. 

Most  modern  machines  are  equipped  with  an  alighting 
gear,  which  not  only  serves  to  protect  the  machine  and 
aviator  from  shock  or  injury  in  touching  the  ground,  but 
also  aids  in  getting  under  headway.  All  the  leading 
makes,  with  the  exception  of  the  Wright,  are  furnished 
with  a  frame  carrying  from  two  to  five  pneumatic  rub- 
ber-tired bicycle  wheels.  In  the  Curtiss  and  Voisin 
machines  one  wheel  is  placed  in  front  and  two  in  the 
rear.  In  the  Bleriot  and  other  prominent  machines  the 


CONSTRUCTION   AND    OPERATION 


74  FLYING   MACHINES: 

reverse  is  the  rule — two  wheels  in  front  and  one  in  the 
rear.  Farman  makes  use  of  five  wheels,  one  in  the, 
extreme  rear,  and  four,  arranged  in  pairs,  a  little  to  the 
front  of  the  center  of  the  main  lower  plane. 

In  place  of  wheels  the  Wright  machine  is  equipped 
with  a  skid-like  device  consisting  of  two  long  beams 
attached  to  the  lower  plane  by  stanchions  and  curving 
up  far  in  front,  so  as  to  act  as  supports  to  the  horizontal 
rudder. 

Why  Wood  Is  Favored. 

A  frequently  asked  question  is :  "Why  is  not  alumi- 
num, or  some  similar  metal,  substituted  for  wood." 
Wood,  particularly  spruce,  is  preferred  because,  weight 
considered,  it  is  much  stronger  than  aluminum,  and  this 
is  the  lightest  of  all  metals.  In  this  connection  the  fol- 
lowing table  will  be  of  interest : 

Compressive 

AVeight  Tensile  Strength         Strength 

per  cubic  foot         per  cubic  foot     per  cr.bic  foot 
Material  in  Ibs.  in  Ibs.  in  Ibs. 

Spruce    25  8,000  5,000 

Aluminum    162  16,000             

Brass  (sheet)   510  23,000  12,000 

Steel    (tool)    490  100,000  40,000 

Copper   (sheet) .  548  30,000  40,000 

As  extreme  lightness,  combined  with  strength, 
especially  tensile  strength,  is  the  great  essential  in  flying- 
machine  construction,  it  can  be  readily  seen  that  the 
use  of  metal,  even  aluminum,  for  the  framework,  is  pro- 
hibited by  its  weight.  While  aluminum  has  double  the 
strength  of  spruce  wood  it  is  vastly  heavier,  and  thus 
the  advantage  it  has  in  strength  is  overbalanced  many 
times  by  its  weight.  The  specific  gravity  of  aluminum 
is  2.50;  that  of  spruce  is  only  0.403. 


CONSTRUCTION   AND    OPERATION 


75 


Things  to  Be  Considered. 

In  laying  out  plans  for  a  flying  machine  there  are  five 
important  points  which  should  be  settled  upon  before 
the  actual  work  of  construction  is  started.  These  are: 

First — Approximate  weight  of  'the  machine  when  fin- 
ished and  equipped. 

Second — Area  of  the  supporting  surface  required. 

Third — Amount  of  power  that  will  be  necessary  to 
secure  the  desired  speed  and  lifting  capacity. 

Fourth — Exact  dimensions  of  the  main  framework 
and  of  the  auxiliary  parts. 


Loose  Joint  Connection  Device. 

Fifth — Size,  speed  and  character  of  the  propeller. 

In  deciding  upon  these  it  will  be  well  to  take  into 
consideration  the  experience  of  expert  aviators  regard- 
ing these  features  as  given  elsewhere.  (See  Chapter  X.) 

Estimating  the  Weights  Involved. 

In  fixing  upon  the  probable  approximate  weight  in 
advance  of  construction  much,  of  course,  must  be;  as- 
sumed. This  means  that  it  will  be  a  matter  of  advance 


70  FLYING   MACHINES: 

estimating.  If  a  two-passenger  machine  is  to  be  built 
we  will  start  by  assuming  the  maximum  combined 
weight  of  the  two  people  to  be  350  pounds.  Most  of 
the  professional  aviators  are  lighter  than  this.  Taking 
the  medium  between  the  weights  of  the  Curtiss  and 
Wright  machines  we  have  a  net  average  of  850  pounds 
for  the  framework,  motor,  propeller,  etc.  This,  with 
the  two  passengers,  amounts  to  1,190  pounds.  As  the 
machines  quoted  are  in  successful  operation  it  will  be 
reasonable  to  assume  that  this  will  be  a  safe  basis  to 
operate  on. 

What  the   Novice  Must  Avoid. 

This  does  not  mean,  however,  that  it  will  be  safe  to 
follow  these  weights  exactly  in  construction,  but  that 
they  will  serve  merely  as  a  basis  to  start  from.  Because 
an  expert  can  turn  out  a  machine,  thoroughly  equipped, 
of  850  pounds  weight,  it  does  not  follow  that  a  novice 
can  do  the  same  thing.  The  expert's  work  is  the  result 
of  years  of  experience,  and  he  has  learned  how  to  con- 
struct frames  and  motor  plants  of  the  utmost  lightness 
and  strength. 

It  will  be  safer  for  the  novice  to  assume  that  he  can 
not  duplicate  the  work  of  such  men  as  Wright  and  Cur- 
tiss without  adding  materially  to  the  gross  weight  of 
the  framework  and  equipment  minus  passengers. 

How  to  Distribute  the  Weight. 

Let  us  take  1,030  pounds  as  the  net  weight  of  the  ma- 
chine as  against  the  same  average  in  the  Wright  and 
Curtiss  machines.  Now  comes  the  question  of  distribu- 
ting this  weight  between  the  framework,  motor,  and 
other  equipment.  As  a  general  proposition  the  frame- 
work should  weigh  about  twrice  as  much  as  the  complete 
power  plant  (this  is  for  amateur  work). 


CONSTRUCTION   AND    OPERATION 


77 


78  FL  YING  •  MA  CHINES : 

The  word  "framework"  indicates  not  only  the  wooden 
frames  of  the  main  planes,  auxiliary  planes,  rudders, 
etc.,  but  the  cloth  coverings  as  well — everything  in  fact 
except  the  engine  and  propeller. 

On  the  basis  named  the  framework  would  weigh  686 
pounds,  and  the  power  plant  344.  These  figures  are 
liberal,  and  the  results  desired  may  be  obtained  well 
within  them  as  the  novice  will  learn  as  he  makes  prog- 
ress in  the  work. 

Figuring  on  Surface  Area. 

It  was  Prof.  Langley  who  first  brought  into  promi- 
nence in  connection  with  flying  machine  construction  the 
mathematical  principle  that  the  larger  the  object  the 
smaller  may  be  the  relative  area  of  support.  As  ex- 
plained in  Chapter  XIII,  there  are  mechanical  limits  as 
to  size  which  it  is  not  practical  to  exceed,  but  the  main 
principle  remains  in  effect. 

Take  two  aeroplanes  of  marked  difference  in  area  of 
surface.  The  larger  will,  as  a  rule,  sustain  a  greater 
weight  in  relative  proportion  to  its  area  than  the  smaller 
one,  and  do  the  work  with  less  relative  horsepower.  As 
a  general  thing  well-constructed  machines  will  average 
a  supporting  capacity  of  one  pound  for  every  one-half 
square  foot  of  surface  area.  Accepting  this  as  a  working 
rule  we  find  that  to  sustain  a  weight  of  1,200  pounds 
— machine  and  two  passengers — we  should  have  600 
square  feet  of  surface. 

Distributing  the  Surface  Area. 

The  largest  surfaces  now  in  use  are  those  of  the 
Wright,  Voisin  and  Antoinette  machines — 538  square 
feet  in  each.  The  actual  sustaining  power  of  these  ma- 
chines, so  far  as  known,  has  never  been  tested  to  the 
limit;  it  is  probable  that  the  maximum  is  considerably 
in  excess  of  what  they  have  been  called  upon  to  show. 


CONSTRUCTION   AND    OPERATION 


79 


Iii  actual  practice  the  average  is  a  little  over  one  pound 
for  each  one-half  square  foot  of  surface  area. 

Allowing  that  600  square  feet  of  surface  will  be  used, 
the  next  question  is  how  to  distribute  it  to  the  best 
advantage.  This  is  another  important  matter  in  which 
individual  preference  must  rule.  We  have  seen  how 
the  professionals  disagree  on  this  point,  some  using 
auxiliary  planes  of  large  size,  and  others  depending  upon 


BEAM         SHORT  /A/vsr 


STRUT  —*» 


.WlRB. 

STAY 


L-Q 

'  Nlfif* 


w^    r 

\ABCUT 

Wiring   and   Beam   Section   of  Van  Anden   Machine. 


smaller  auxiliaries  with  an  increase  in  number  so  as  to 
secure  on  a  different  plan  virtually  the  same  amount  of 
surface. 

In  deciding  upon  this  feature  the  best  thing  to  do  is 
to  follow  the  plans  of  some  successful  aviator,  increasing 


80  FLYING   MACHINES: 

the  area  of  the  auxiliaries  in  proportion  to  the  increase 
in  the  area  of  the  main  planes.  Thus,  if  you  use  600 
square  feet  of  surface  where  the  man  whose  plans  you 
are  following  uses  500,  it  is  simply  a  matter  of  making 
your  planes  one-fifth  larger  all  around. 

The  Cost  of  Production. 

Cost  of  production  will  be  of  interest  to  the  amateur 
who  essays  to  construct  a  flying  machine.  Assuming 
that  the  size  decided  upon  is  double  that  of  the  glider 
the  material  for  the  framework,  timber,  cloth,  wire,  etc., 
will  cost  a  little  more  than  double.  This  is  because  it 
must  be  heavier  in  proportion  to  the  increased  size  of 
the  framework,  and  heavy  material  brings  a  larger  price 
than  the  lighter  goods.  If  we  allow  $20  as  the  cost  of 
the  glider  material  it  will  be  safe  to  put  down  the  cost 
of  that  required  for  a  real  flying  machine  framework 
at  $60,  provided  the  owner  builds  it  himself. 

As  regards  the  cost  of  motor  and  similar  equipment 
it  can  only  be  said  that  this  depends  upon  the  selection 
made.  There  are  some  reliable  aviation  motors  which 
may  be  had  as  low  as  $500,  and  there  are  others  which 
cost  as  much  as  $2,000. 

Services  of  Expert  Necessary. 

No  matter  what  kind  of  a  motor  may  be  selected  the 
services  of  an  expert  will  be  necessary  in  its  proper 
installation  unless  the  amateur  has  considerable  genius 
in  this  line  himself.  As  a  general  thing  $25  should  be 
a  liberal  allowance  for  this  work.  No  matter  how  care- 
fully the  engine  may  be  placed  and  connected  it  will  be 
largely  a  matter  of  luck  if  it  is  installed  in  exactly  the 
proper  manner  at  the  first  attempt.  The  chances  are 
that  several  alterations,  prompted  by  the  results  of  trials, 
will  have  to  be  made.  If  this  is  the  case  the  expert's 


CONSTRUCTION  AND   OPERATION 


81 


bill  may  readily  run  up 
to  $50.  If  the  amateur 
is  competent  to  do  this 
part  of  the  wor.k  the 
entire  item  of  $50  may, 
of  course,  be  cut  out. 

As  a  general  propo- 
sition a  fairly  satisfac- 
tory flying  machine, 
one  that  will  actually 
fly  and  carry  the  oper- 
ator with  it,  may  be 
constructed  for  $750, 
but  it  will  lack  the  bet- 
ter qualities  which 
mark  the  higher  priced 
machines.  This  com- 
putation is  made  on 
the  basis  of  $60  for  ma- 
terial, $50  for  services 
of  expert,  $600  for  mo- 
tor, etc.,  and  an  allow- 
ance of  $40  for  extras. 

No  man  who  has  the 
flying  machine  germ  in 
his  system  will  be  long 
satisfied  with  his  first 
moderate  price  ma- 
chine, no  matter  how 
well  it  may  work.  It's 
the  old  story  of  the 
automobile  "bug"  over 
again.  The  man  who 
starts  in  with  a  modest 
$1,000  automobile  in- 
variably progresses  by 


82  FLYING   MACHINES: 

easy  stages  to  the  $4,000  or  $5,000  class.  The  natural 
tendency  is  to  want  the  biggest  and  best  attainable 
within  the  financial  reach  of  the  owner. 

It's  exactly  the  same  way  with  the  flying  machine 
convert.  The  more  proficient  he  becomes  in  the  manipu- 
lation of  his  car,  the  stronger  becomes  the  desire  to  fly 
further  and  stay  in  the  air  longer  than  the  rest  of  his 
brethren.  This  necessitates  larger,  more  powerful,  and 
more  expensive  machines  as  the  work  of  the  germ  pro- 
gresses. 

Speed  Affects  Weight  Capacity. 

Don't  overlook  the  fact  that  the  greater  speed  you 
can  attain  the  smaller  will  be  the  surface  area  you  can 
get  along  with.  If  a  machine  with  500  square  feet  of 
sustaining  surface,  traveling  at  a  speed  of  40  miles  an 
hour,  will  carry  a  weight  of  1,200  pounds,  we  can  cut 
the  sustaining  surface  in  half  and  get  along  with  250 
square  feet,  provided  a  speed  of  60  miles  an  hour  can 
be  obtained.  At  100  miles  an  hour  only  80  square  feet 
of  surface  area  wrould  be  required.  In  both  instances  the 
weight  sustaining  capacity  will  remain  the  same  as  with 
the  500  square  feet  of  surface  area — 1,200  pounds. 

One  of  these  days  some  mathematical  genius  will 
figure  out  this  problem  with  exactitude  and  we  will  have 
a  dependable  table  giving  the  maximum  carrying  capac- 
ity of  various  surface  areas  at  various  stated  speeds, 
based  on  the  dimensions  of  the  advancing  edges.  At 
present  it  is  largely  a  matter  of  guesswork  so  far  as 
making  accurate  computation  goes.  Much  depends  up- 
on the  shape  of  the  machine,  and  the  amount  of  surface 
offering  resistance  to  the  wind,  etc. 


CHAPTER  IX. 

SELECTION  OF  THE  MOTOR. 

Motors  for  flying  machines  must  be  light  in  weight, 
of  great  strength,  productive  of  extreme  speed,  and 
positively  dependable  in  action.  It  matters  little 
as  to  the  particular  form,  or  whether  air  or 
water  cooled,  so  long  as  the  four  features  named  are 
secured.  There  are  at  least  a  dozen  such  motors  or 
engines  now  in  use.  All  are  of  the  gasolene  type,  and 
all  possess  in  greater  or  lesser  degree  the  desired  quali- 
ties. Some  of  these  motors  are : 

Renault — 8-cylinder,  air-cooled;  50  horse  power; 
weight  374  pounds. 

Fiat — 8-cylinder,  air-cooled ;  50  horse  power ;  weight 
150  pounds. 

Farcot — 8-cylinder,  air-cooled ;  from  30  to  100  horse 
power,  according  to  bore  of  cylinders ;  weight  of  smallest, 
84  pounds. 

R.  E.  P. —  io-cylinder,  air-cooled;  150  horse  power; 
weight  215  pounds. 

Gnome — 7  and  14  cylinders,  revolving  type,  air-cooled ; 
50  and  100  horse  power;  weight  150  and  300  pounds. 

Darracq — 2  to  14  cylinders,  water  cooled ;  30  to  200 
horse  power ;  weight  of  smallest,  100  pounds. 

Wright — 4-cylinder,  water-cooled ;  25  horse  power ; 
weight  200  pounds. 

Antoinette — 8  and  i6-cylinder,  water-cooled  ;  50  and  100 
horse  power;  weight  250  and  500  pounds. 

E.   N.   V. — 8-cylinder,  water-cooled;   from   30    to    86 


84  FLYING   MACHINES: 

horse  power,  according  to  bore  of  cylinder;  weight  150 
to  400  pounds. 

Curtiss — 8-cylinder,  water-cooled ;  60  horse  power ; 
weight  300  pounds. 

Average  Weight  Per  Horse  Power. 

It  will  be  noticed  that  the  Gnome  motor  is  unusually 
light,  being  about  three  pounds  to  the  horse  power 
produced,  as  opposed  to  an  average  of  ^l/2  pounds  per 
horse  power  in  other  makes.  This  result  is  secured  by 
the  elimination  of  the  fly-wheel,  the  engine  itself  revolv- 
ing, thus  obtaining  the  same  effect  that  would  be  pro- 
duced by  a  fly-wheel.  The  Farcot  is  even  lighter,  being 
considerably  less  than  three  pounds  per  horse  power, 
which  is  the  nearest  approach  to  the  long-sought  engine 
equipment  that  will  make  possible  a  complete  flying 
machine  the  total  weight  of  which  will  not  exceed  one 
pound  per  square  foot  of  area. 

How  Lightness  Is  Secured. 

Thus  far  foreign  manufacturers  are  ahead  of  Amer- 
icans in  the  production  of  light-weight  aerial  motors,  as 
is  evidenced  by  the  Gnome  and  Farcot  engines,  both  of 
which  are  of  French  make.  Extreme  lightness  is  made 
possible  by  the  use  of  fine,  specially  prepared  steel  for 
the  cylinders,  thus  permitting  them  to  be  much  thinner 
than  if  ordinary  forms  of  steel  were  used.  Another  big 
saving  in  weight  is  made  by  substituting  what  are 
known  as  "auto  lubricating"  alloys  for  bearings.  These 
alloys  are  made  of  a  combination  of  aluminum  and  mag- 
nesium. 

Still  further  gains  are  made  in  the  use  of  alloy  steel 
tubing  instead  of  solid  rods,  and  also  by  the  paring  away 
of  material  wherever  it  can  be  dpne  without  sacrificing 
strength.  This  plan,  with  the  exclusive  use  of  the  best 


CONSTRUCTION   AND    OPERATION 


85 


grades   of   steel,   regardless   of   cost,   makes    possible    a 
marked  reduction  in  weight. 

Multiplicity  of  Cylinders. 

Strange  as  it  may  seem,  multiplicity  of  cylinders  does 
not  always  add  proportionate  weight.  Because  a  4- 
cylinder  motor  weighs  say  100  pounds,  it  does  not  neces- 
sarily follow  that  an  8-cylinder  equipment  will  weigh 
200  pounds.  The  reason  of  this  will  be  plain  when  it 


Tilting    Motor   on   L.    A.   W.   Aeroplane. 

Upper  cut  shows  motor  tilted  when  machine  is  leaving  the 
ground.  Lower  cut  shows  motor  in  horizontal  position  when  ma- 
chine is  flying. 

is  understood  that  many  of  the  parts  essential  to  a  4- 
cylinder  motor  will  fill  the  requirements  of  an  8-cylinder 
motor  without  enlargement  or  addition. 

Neither    does    multiplying   the     cylinders    always    in- 
crease the  horsepower  proportionately.     If  a  4-cylinder 


86 


FLYING   MACHINES: 


motor  is  rated  at  25  horsepower  it  is  not  safe  to  take 
it  for  granted  that  double  the  number  of  cylinders  will 
give  50  horsepower.  Generally  speaking,  eight  cylinders, 
the  bore,  stroke  and  speed  being  the  same,  will  give 
double  the  power  that  can  be  obtained  from  four,  but 
this  does  not  always  hold  good.  Just  why  this  exception 
should  occur  is  not  explainable  by  any  accepted  rule. 

Horse  Power  and  Speed. 

Speed  is  an  important  requisite  in  a  flying-machine 
motor,  as  the  velocity  of  the  aeroplane  is  a  vital  factor 
in  flotation.  At  first  thought,  the  propeller  and  similar 


Method   of  Attaching   Gnome   Motor. 

adjuncts  being  equal,  the  inexperienced  mind  would 
naturally  argue  that  a  5o-horsepower  engine  should 
produce  just  double  the  speed  of  one  of  25-horsepower. 
That  this  is  a  fallacy  is  shown  by  actual  performances. 
The  Wrights,  using  a  25-horsepower  motor,  have  made 
44  miles  an  hour,  while  Bleriot,  with  a  5O-horsepower 
motor,  has  a  record  of  a  short-distance  flight  at  the  rate 
of  52  miles  an  hour.  The  fact  is  that,  so  far  as  speed 
is  concerned,  much  depends  upon  the  velocity  of  the 
wind,  the  size  and  shape  of  the  aeroplane  itself,  and  the 


CONSTRUCTION   AND   OPERATION 


87 


O      CQ 

II 

o<    .. 

O    ^ 


2    P 

O 

I 


O       cs 

S 


o    5 

1  i 


88  FLYING   MACHINES: 

size,  shape  and  gearing  of  the  propeller.  The  stronger 
the  wind  is  blowing  the  easier  it  will  be  for  the  aero- 
plane to  ascend,  but  at  the  same  time  the  more  difficult 
it  will  be  to  make  headway  against  the  wind  in  a  hori- 
zontal direction.  With  a  strong  head  wind,  and  proper 
engine  force,  your  machine  will  progress  to  a  certain 
extent,  but  it  will  be  at  an  angle.  If  the  aviator  desired 
to  keep  on  going  upward  this  would  be  all  right,  but 
there  is  a  limit  to  the  altitude  which  it  is  desirable  to 
reach — from  100  to  500  feet  for  experts — and  after  that 
it  becomes  a  question  of  going  straight  ahead. 

Great  Waste  of  Power. 

One  thing  is  certain — even  in  the  most  efficient  of 
modern  aerial  motors  there  is  a  great  loss  of  power  be- 
tween the  two  points  of  production  and  effect.  The 
Wright  outfit,  which  is  admittedly  one  of  the  most  ef- 
fective in  use,  takes  one  horsepower  of  force  for  the  rais- 
ing and  propulsion  of  each  50  pounds  of  weight.  This, 
for  a  25-horsepower  engine,  would  give  a  maximum  lift- 
ing capacity  of  1250  pounds.  It  is  doubtful  if  any  of  the 
higher  rated  motors  have  greater  efficiency.  As  an  8- 
cylinder  motor  requires  more  fuel  to  operate  than  a  4- 
cylinder,  it  naturally  follows  that  it  is  more  expensive 
to  run  than  the  smaller  motor,  and  a  normal  increase  in 
capacity,  taking  actual  performances  as  a  criterion,  is 
lacking.  In  other  words,  what  is  the  sense  of  using  an 
8-cylinder  motor  when  one  of  4  cylinders  is  sufficient? 

What  the  Propeller  Does. 

Much  of  the  efficiency  of  the  motor  is  due  to  the  form 
and  gearing  of  the  propeller.  Here  again,  as  in  other 
vital  parts  of  flying-machine  mechanism,  we  have  a  wide 
divergence  of  opinion  as  to  the  best  form.  A  fish  makes 
progress  through  the  water  by  using  its  fins  and  tail ; 


CONSTRUCTION  AND    OPERATION 


89 


a  bird  makes  its  way  through  the  air  in  a  similar  manner 
by  the  use  of  its  wings  and  tail.  In  both  instances  the 
motive  power  comes  from  the  body  of  the  fish  or  bird. 


New  French  System  of  Steering  by  Propeller. 

A — motor  shaft;  B — differential;  C — pinion  gear  on  main  shaft 
A.  Two  propellers  H,  H,  are  used;  C — gears  by  which  are  driven 
by  shafts  running  from  the  differential  B.  These  propellers  are 
used  in  steering.  F  shows  the  application  of  the  steering  cables 


In  place  of  fins  or  wings  the  flying  machine  is  equipped 
with  a  propeller,  the  action  of  which  is  furnished  by  the 
engine.  Fins  and  wings  have  been  tried,  but  they  don't 
work. 


90  FLYING   MACHINES: 

While  operating  on  the  same  general  principle,  aerial 
propellers  are  much  larger  than  those  used  on  boats. 
This  is  because  the  boat  propeller  has  a  denser,  more 
substantial  medium  to  work  in  (water),  and  consequent- 
ly can  get  a  better  "hold,"  and  produce  more  propulsive 
force  than  one  of  the  same  size  revolving  in  the  air. 
This  necessitates  the  aerial  propellers  being  much  larger 
than  those  employed  for  marine  purposes.  Up  to  this 
point  all  aviators  agree,  but  as  to  the  best  form  most  of 
them  differ. 

Kinds  of  Propellers  Used. 

One  of  the  most  simple  is  that  used  by  Curtiss.  It 
consists  of  two  pear-shaped  blades  of  laminated  wood, 
each  blade  being  5  inches  wide  at  its  extreme  point, 
tapering  slightly  to  the  shaft  connection.  These  blades 
are  joined  at  the  engine  shaft,  in  a  direct  line.  The  pro- 
peller has  a  pitch  of  5  feet,  and  weighs,  complete,  less 
than  10  pounds.  The  length  from  end  to  end  of  the  two 
blades  is  6y2  feet. 

Wright  uses  two  wooden  propellers,  in  the  rear  of  his 
biplane,  revolving  in  opposite  directions.  Each  propeller 
is  two-bladed. 

Bleriot  also  uses  a  two-blade  wooden  propeller,  but 
it  is  placed  in  front  of  his  machine.  The  blades  are  each 
about  33/2  feet  long  and  have  an  acute  "twist." 

Santos-Dumont  uses  a  two-blade  wooden  propeller, 
strikingly  similar  to  the  Bleriot. 

On  the  Antoinette  monoplane,  with  which  good  records 
have  been  made,  the  propeller  consists  of  two  spoon-x 
shaped  pieces  of  metal,  joined  at  the  engine  shaft  in 
front,  and  with  the  concave  surfaces  facing  the  machine. 

The  propeller  on  the  Voisin  biplane  is  also  of  metal, 
consisting  of  two  aluminum  blades  connected  by  a  forged 
steel  arm. 

Maximum   thrust,   or   stress — exercise   of   the   greatest 


CONSTRUCTION   AND    OPERATION 


91 


air-displacing  force — is  the  object  sought.  This,  accord- 
ing to  experts,  is  best  obtained  with  a  large  propeller 
diameter  and  reasonably  low  speed.  The  diameter  is  the 
distance  from  end  to  end  of  the  blades,  which  on  the 
largest  propellers  ranges  from  6  to  8  feet.  The  larger 
the  blade  surface  the  greater  will  be  the  volume  of  air 
displaced,  and,  following  this,  the  greater  will  be  the 
impulse  which  forces  the  aeroplane  ahead.  In  all  cen- 
trifugal motion  there  is  more  or  less  tendency  to  disin- 
tegration in  the  form  of  "flying  off"  from  the  center,  and 


Seat  and  Motor  on  Farman  Machine. 

the  larger  the  revolving  object  is  the  stronger  is  this 
tendency.  This  is  illustrated  in  the  many  instances  in 
which  big  grindstones  and  fly-wheels  have  burst  from 
being  revolved  too  fast.  To  have  a  propeller  break 
apart  in  the  air  would  jeopardize  the  life  of  the  aviator, 
and  to  guard  against  this  it  has  been  found  best  to  make 
its  revolving  action  comparatively  slow.  Besides  this 
the  slow  motion  (it  is  only  comparatively  slow)  gives 
the  atmosphere  a  chance  to  refill  the  area  disturbed  by 


92  FLYING   MACHINES: 

one   propeller  blade,   and  thus   have  a  new  surface   for 
the  next  blade  to  act  upon. 

Placing  of  the  Motor. 

As  on  other  points,  aviators  differ  widely  in  their 
ideas  as  to  the  proper  position  for  the  motor.  Wright 
locates  his  on  the  lower  plane,  midway  between  the  front 
and  rear  edges,  but  considerably  to  one  side  of  the  exact 
center.  He  then  counter-balances  the  engine  weight  by 
placing  his  seat  far  enough  away  in  the  opposite  direc- 
tion to  preserve  the  center  of  gravity.  This  leaves  a 
space  in  the  center  between  the  motor  and  the  operator 
in  which  a  passenger  may  be  carried  without  disturb- 
ing the  equilibrium. 

Bleriot,  on  the  contrary,  has  his  motor  directly  in 
front  and  preserves  the  center  of  gravity  by  taking  his 
seat  well  back,  this,  with  the  weight  of  the  aeroplane, 
acting  as  a  counter-balance. 

On  the  Curtiss  machine  the  motor  is  in  the  rear,  the 
forward  seat  of  the  operator,  and  weight  of  the  horizon- 
tal rudder  and  damping  plane  in  front  equalizing  the 
engine  weight. 

No   Perfect  Motor  as   Yet. 

Engine  makers  in  the  United  States,  England,  France 
and  Germany  are  all  seeking  to  produce  an  ideal  motor 
for  aviation  purposes.  Many  of  the  productions  are 
highly  creditable,  but  it  may  be  truthfully  said  that 
none  of  them  quite  fill  the  bill  as  regards  a  combina- 
tion of  the  minimum  of  weight  with  the  maximum  of 
reliable  maintained  power.  They  are  all,  in  some  re- 
spects, improvements  upon  those  previously  in  use,  but 
the  great  end  sought  for  has  not  been  fully  attained. 

One  of  the  motors  thus  produced  was  made  by  the 
French  firm  of  Darracq  at  the  suggestion  of  Santos  Du- 


CONSTRUCTION  AND   OPERATION 


93 


mont,  and  on  lines  laid  down  by  him.  Santos  Dumont 
wanted  a  2-cylinder  horizontal  motor  capable  of  devel- 
oping- 30  horsepower,  and  not  exceeding  4^  pounds  per 
horsepower  in  weight. 

There  can  be  no  question  as  to  the  ability  and  skill 


Propeller  and  Motor  on  Voisin  Machine. 


of  the  Darracq  people,  or  of  their  desire  to  produce  a 
motor  that  would  bring  new  credit  and  prominence  to 
the  firm.  Neither  could  anything  radically  wrong  be 


94  FLYING   MACHINES: 

detected  in  the  plans.  But  the  motor,  in  at  least  one 
important  requirement,  fell  short  of  expectations. 

It  could  not  be  depended  upon  to  deliver  an  energy 
of  30  horsepower  continuously  for  any  length  of  time. 
Its  maximum  power  could  be  secured  only  in  "spurts." 

This  tends  to  show  how  hard  it  is  to  produce  an  ideal 
motor  for  aviation  purposes.  Santos  Dumont,  of  un- 
doubted skill  and  experience  as  an  aviator,  outlined  defi- 
nitely what  he  wanted ;  one  of  the  greatest  designers 
in  the  business  drew  the  plans,  and  the  famous  house  of 
Darracq  bent  its  best  energies  to  the  production.  But 
the.  desired  end  was  not  fully  attained. 

Features  of  Darracq  Motor. 

Horizontal  motors  were  practically  abandoned  some 
time  ago  in  favor  of  the  vertical  type,  but  Santos  Du- 
mont had  a  logical  reason  for  reverting  to  them.  He 
wanted  to  secure  a  lower  center  of  gravity  than  would 
be  possible  with  a  vertical  engine.  Theoretically  his 
idea  was  correct  as  the  horizontal  motor  lies  flat,  and 
therefore  offers  less  resistance  to  the  wind,  but  it  did  not 
work  out  as  desired. 

'At  the  same  time  it  must  be  admitted  that  this  Dar- 
racq motor  is  a  marvel  of  ingenuity  and  exquisite  work- 
manship. The  two  cylinders,  having  a  bore  of  5  i-io 
inches  and  a  stroke  of  4  7-10  inches,  are  machined  out 
of  a  solid  bar  of  steel  until  their  weight  is  only  8  4-5 
pounds  complete.  The  head  is  separate,  carrying  the 
seatings  for  the  inlet  and  exhaust  valves,  is  screwed  onto 
the  cylinder,  and  then  welded  in  position.  A  copper 
water-jacket  is  fitted,  and  it  is  in  this  condition  that  the 
weight  of  8  4-5  pounds  is  obtained. 

On  long  trips,  especially  in  regions  where  gasolene  is 
hard  to  get,  the  weight  of  the  fuel  supply  is  an  impor- 
tant feature  in  aviation.  As  a  natural  consequence  flying 


CONSTRUCTION   AND    OPERATION  95 

machine  operators  favor  the  motor  of  greatest  economy 
in  gasolene  consumption,  provided  it  gives  the  necessary 
power. 

An  American  inventor,  Ramsey  by  name,  is  working 
on  a  motor  which  is  said  to  possess  gfeat  possibilities 
in  this  line.  Its  distinctive  features  include  a  connecting 


Sectional  View  of  Ramsey  Motor. 

rod  much  shorter  than  usual,  and  a  crank  shaft  located 
the  length  of  the  crank  from  the  central  axis  of  the 
cylinder.  This  has  the  effect  of  increasing  the  piston 
stroke,  and  also  of  increasing  the  proportion  of  the 
crank  circle  during  which  effective  pressure  is  applied 
to  the  crank. 

Making  the  connecting  rod  shorter  and  leaving  the 
crank  mechanism  the  same  would  introduce  excessive 
cylinder  friction.  This  Ramsey  overcomes  by  the  loca- 
tion of  his  crank  shaft.  The  effect  of  the  long  piston 


96  FLYING   MACHINES: 

stroke  thus  secured,  is  to  increase  the  expansion  of  the 
gases,  which  in  turn  increases  the  power  of  the  engine 
without  increasing  the  amount  of  fuel  used. 

Propeller  Thrust  Important. 

There  is  one  great  principle  in  flying  machine  propul- 
sion which  must  not  be  overlooked.  No  matter  how 
powerful  the  engine  may  be  unless  the  propeller  thrust 
more  than  overcomes  the  wind  pressure  there  can  be 
no  progress  forward.  Should  the  force  of  this  propeller 
thrust  and  that  of  the  wind  pressure  be  equal  the  re- 
sult is  obvious.  The  machine  is  at  a  stand-still  so  far 
as  forward  progress  is  concerned  and,  deprived  of  the 
essential  advancing  movement,  falls  to  the  ground.^ 

Speed  not  only  furnishes  sustentation  for  the  airship, 
but  adds  to  the  stability  of  the  machine.  An  aeroplane 
which  may  be  jerky  and  uncertain  in  its  movements,  so 
far  as  equilibrium  is  concerned,  when  moving  at  a  slow 
gait,  will  readily  maintain  an  even  keel  when  the  speed 
is  increased. 

Designs  for  Propeller  Blades. 

It  is  the  object  of  all  men  who  design  propellers  to 
obtain  the  maximum  of  thrust  with  the  minimum  ex- 
penditure of  engine  energy.  With  this  purpose  in  view 
many  peculiar  forms  of  propeller  blades  have  been 
evolved.  In  theory  it  would  seem  that  the  best  effects 
could  be  secured  with  blades  so  shaped  as  to  present  a 
thin  (or  cutting)  edge  when  they  come  out  of  the  wind, 
and  then  at  the  climax  of  displacement  afford  a  maxi- 
mum of  surface  so  as  to  displace  as  much  air  as  pos- 
sible. While  this  is  the  form  most  generally  favored 
there  are  others  in  successful  operation. 

There  is  also  wide  difference  in  opinion  as  to  the 
equipment  of  the  propeller  shaft  with  two  or  more 


CONSTRUCTION   AND    OPERATION 


97 


blades.  Some  aviators  use  two  and  some  four.  All 
have  more  or  less  success.  As  a  mathematical  proposi- 
tion it  would  seem  that  four  blades  should  give  more 
propulsive  force  than  two,  but  here  again  comes  in  one 
of  the  puzzles  of  aviation,  as  this  result  is  not  always 
obtained. 

Difference  in  Propeller  Efficiency. 

That  there  is  a  great  difference  in  propeller  efficiency 
is  made  readily  apparent  by  the   comparison  of  effects 


r    .      ft*.        «i 


Engine  and  Propeller  of  Curtiss  Biplane. 


produced  in  two  leading  makes  of  machines — the  Wright 
and  the  Voisin. 

In  the  former  a  weight  of  from  1,100  to  1,200  pounds 
is  sustained  and  advance  progress  made  at  the  rate  of 
40  miles  an  hour  and  more,  with  half  the  engine  speed 
of  a  25  horse-power  motor.  This  would  be  a  sustaining. 


98  FLYING   MACHINES: 

capacity  of  48  pounds  per  horsepower.  But  the  actual 
capacity  of  the  Wright  machine,  as  already  stated,  is  50 
pounds  per  horsepower. 

The  Voisin  machine,  with  aviator,  weighs  about  1,3/0 
pounds,   and   is   operated   with   a    5O-horsepower   motor. 


One  of  the  Four-Bladed  Propellers. 


Allowing  it  the  same  speed  as  the  Wright  we  find  that, 
with  double  the  engine  energy,  the  lifting  capacity  is 
only  27^  pounds  per  horsepower.  To  what  shall  we 
charge  this  remarkable  difference?  The  surface  of  the 


CONSTRUCTION   AND    OPERATION 


99 


planes   is   exactly   the   same   in   both   machines  so   there 
is  no  advantage  in  the  matter  of  supporting  area. 

Comparison  of  Two  Designs. 

On  the  Wright  machine  two  wooden  propellers  of 
two  blades  each  (each  blade  having  a  decided  "twist") 
are  used.  As  one  25  horsepower  motor  drives  both  pro- 


A  Three-Bladed  Propeller. 

pellers  the  engine  energy  amounts  to  just  one-half  of 
this  for  each,  or  i2l/2  horsepower.  And  this  energy  is 
utilized  at  one-half  the  normal  engine  speed. 

On  the  Voisin  a  radically  different  system  is  employed. 
Here  we  have  one  metal  two-bladed  propeller  with  a 
very  slight  "twist"  to  the  blade  surfaces.  The  full  energy 
of  a  5o-horsepower  motor  is  utilized. 

Experts  Fail  to  Agree. 

Why  should  there  be  such  a  marked  difference  in 
the  results  obtained?  Who  knows?  Some  experts 


100  FLYING   MACHINES: 

maintain  that  it  is  because  there  are  two  propellers  on 
the  Wright  machine  and  only  one  on  the  Voisin,  and 
consequently  double  the  propulsive  power  is  exerted. 
But  this  is  not  a  fair  deduction,  unless  both  propellers 
are  of  the  same  size.  Propulsive  power  depends  upon 
the  amount  of  air  displaced,  and  the  energy  put  into  the 
thrust  which  displaces  the  air. 

Other  experts  argue  that  the  difference  in  results  may 


Sample  of  Two-Bladed  Propeller. 

be   traced  to   the   difference   in   blade   design,   especially 
in  the  matter  of  "twist." 

The  fact  is  that  propeller  results  depend  largely  upon 
the  nature  of  the  aeroplanes  on  which  they  are  used. 
A  propeller,  for  instance,  which  gives  excellent  results 
on  one  type  of  aeroplane,  will  not  work  satisfactorily  on 
another. 


Simple  Form  of  Propeller  Used  by  Curtiss. 

There  are  some  features,  however,  which  may  be  safe- 
ly adopted  in  propeller  selection.  These  are :  As  exten- 
sive a  diameter  as  possible;  blade  area  10  to  15  per  cent 
of  the  area  swept ;  pitch  four-fifths  of  the  diameter ;  ro- 
tation slow.  The  maximum  of  thrust  effort  will  be  thus 
obtained. 


CHAPTER  X. 

PROPER  DIMENSIONS  OF  MACHINES. 

In  laying  out  plans  for  a  flying  machine  the  first  thing 
to  decide  upon  is  the  size  of  the  plane  surfaces.  The  pro- 
portions of  these  must  be  based  upon  the  load  to  be 
carried.  This  includes  the  total  weight  of  the  machine 
and  equipment,  and  also  the  operator.  This  will  be  a 
rather  difficult  problem  to  'figure  out  exactly,  but  prac- 
tical approximate  figures  may  be  reached. 

It  is  easy  to  get  at  the  weight  of  the  operator,  motor 
and  propeller,  but  the  matter  of  determining,  before  they 
are  constructed,  what  the  planes,  rudders,  auxiliaries, 
etc.,  will  weigh  when  completed  is  an  intricate  proposi- 
tion. The  best  way  is  to  take  the  dimensions  of  some 
successful  machine  and  use  them,  making  such  altera- 
tions in  a  minor  way  as  you  may  desire. 

Dimensions  of  Leading  Machines. 

In  the  following  tables  will  be  found  the  details  as  to 
surface  area,  weight,  power,  etc.,  of  the  nine  principal 
types  of  flying  machines  which  are  now  prominently  be- 
fore the  public : 

MONOPLANES. 


Make 

Santos-Dumont 
Bleriot 

Passengers 
I 
I 

Surface  area 
sq.  feet 

no 
150.6 

Spread  in 
linear  feet 

16.0 

24.  6 

Depth  in 
linear  feet 

26.O 
22.O 

R.  E.  P  

I 

2m 

•^T-<W 

^4.1 

28.Q 

Bleriot    

...  .2 

j 
236 

vTT 
"32.  Q 

.7 
2^.O 

Antoinette    .  .  .  .  , 

,  .  .  .  .2 

•"O 

S^8 

O          .7 

41.2 

•"O 

^7.Q 

JO 

101 

*f  *  fffH 

O/  '.7 

102 


FLYING   MACHINES: 


\o,  of 
Make  Cylinders 

Santos-Dumont    2 

Bleriot    3 

R.   E.   P 7 

Bleriot    8 

Antoinette  ..8 


Weight  Without 
Horse  Power         Operator 


30 
25 
35 
50 
50 


BIPLANES. 

Surface  Area 
Passengers         sq.  feet 


Make 

Curtiss    2 

Wright   2 

Farman    2 

Voisin    2 

No.  of 
Make  Cylinders 

Curtiss    .8 

Wright    4 

Farman   7 

Voisin  ..8 


258 
538 
430 
538 


250 

680 

900 

1,240 

1,040 


Spread  in 
linear  feet 

29.0 
4I.O 
32.9 

37-9 


Horse  Power 
50 

Weight  Without 
Operator 

600 

25 

I,IOO 

50 

1,200 

50 

I,2OO 

Propeller 
Diameter 


6.9 

6.6 
8.1 
7.2 


Depth  in 
linear  feet 

28.7 
30-7 

39-6 
39-6 

Propeller 
Diameter 

6.0 
8.1 
8.9 
6.6 


In  giving  the  depth  dimensions  the  length  over  all — 
from  the  extreme  edge  of  the  front  auxiliary  plane  to 
the  extreme  tip  of  the  rear  is  stated.  Thus  while  the 
dimensions  of  the  main  planes  of  the  Wright  machine 
are  41  feet  spread  by  6l/2  feet  in  depth,  the  depth  over 
all  is  30.7. 

Figuring  Out  the  Details. 

With  this  data  as  a  guide  it  should  be  comparatively 
easy  to  decide  upon  the  dimensions  of  the  machine  re- 
quired. In  arriving  at  the  maximum  lifting  capacity  the 
weight  of  the  operator  must  be  added.  Assuming  this 
to  average  170  pounds  the  method  of  procedure  would  be 
as  follows: 

Add  the  weight  of  the  operator  to  the  weight  of  the 
complete  machine.  The  new  Wright  machine  complete 


CONSTRUCTION   AND    OPERATION 


103 


weighs  900  pounds.  This,  plus  170,  the  weight  of  the 
operator,  gives  a  total  of  1,070  pounds.  There  are  538 
square  feet  of  supporting  surface,  or  practically  one 
square  foot  of  surface  area  to  each  two  pounds  of  load. 


Method  of  Carrying  Passenger  in  Wright  Machine. 

Placing  passenger  in  center   equalizes  weight  between  operator 
and  motor. 


There  are  some  machines,  notably  the  Bleriot,  in  which 
the  supporting  power  is  much  greater.  In  this  latter 
instance  we  find  a  surface  area  of  150^  square  feet 
carrying  a  load  of  680  plus  170,  or  an  aggregate  of  850 
pounds.  This  is  the  equivalent  of  five  pounds  to  the 


104  FLYING   MACHINES: 

square   foot.     This   ratio    is    phenomenally    large,    and 
should  not  be  taken  as  a  guide  by  amateurs. 

The  Matter  of  Passengers. 

These  deductions  are  based  on  each  machine  carrying 
one  passenger,  which  is  admittedly  the  limit  at  present 
of  the  monoplanes  like  those  operated  for  record-making 
purposes  by  Santos-Dumont  and  Bleriot.  The  biplanes, 
however,  have  a  two-passenger  capacity,  and  this  adds 
materially  to  the  proportion  of  their  weight-sustaining 
power  as  compared  with  the  surface  area.  In  the  fol- 
lowing statement  all  the  machines  are  figured  on  the 
one-passenger  basis.  Curtiss  and  Wright  have  carried 
two  passengers  on  numerous  occasions,  and  an  extra  170 
pounds  should  therefore  be  added  to  the  total  weight 
carried,  which  would  materially  increase  the  capacity. 
Even  with  the  two-passenger  load  the  limit  is  by  no 
means  reached,  but  as  experiments  have  gone  no  further 
it  is  impossible  to  make  more  accurate  figures. 

Average  Proportions  of  Load. 

It  will  be  interesting,  before  proceeding  to  lay  out  the 
dimension  details,  to  make  a  comparison  of  the  propor- 
tion of  load  effect  with  the  supporting  surfaces  of  various 
well-known  machines.  Here  are  the  figures : 

Santos-Dumont — A  trifle  under  four  pounds  per  square 
foot. 

Bleriot — Five  pounds. 

R.  E.  P. — Five  pounds. 

Antoinette — About  two  and  one-quarter  pounds. 

Curtiss — About  two  and  one-half  pounds. 

Wright — Two  and  one-quarter  pounds. 

Farman — A  trifle  over  three  pounds. 

Voisin — A   little   under   two   and   one-half   pounds. 


CONSTRUCTION  AND   OPERATION 


105 


Importance  of  Engine  Power. 

While  these  figures  are  authentic,  they  are  in  a  way 
misleading,  as  the  important  factor  of  engine  power 
is  not  taken  into  consideration.  Let  us  recall  the  fact 
that  it  is  the  engine  power  which  keeps  the  machine  in 
motion,  and  that  it  is  only  while  in  motion  that  the  ma- 
chine will  remain  suspended  in  the  air.  Hence,  to  at- 


Striking  Similarity  in  Skeletons  of  Man  and  Bird. 

Skeleton    of   bird    enlarged    for   purpose   of   comparison. 


tribute  the  support  solely  to  the  surface  area  is  erroneous. 
True,  that  once  under  headway  the  planes  contribute 
largely  to  the  sustaining  effect,  and  are  absolutely  essen- 
tial in  aerial  navigation — the  motor  could  not  rise  with- 
out them — still,  when  it  comes  to  a  question  of  weight- 
sustaining  power,  we  must  also  figure  on  the  engine 
capacity. 


106  FLYING   MACHINES: 

In  the  Wright  machine,  in  which  there  is  a  lifting 
capacity  of  approximately  21/^  pounds  to  the  square  foot 
of  surface  area,  an  engine  of  only  25  horsepower  is  used. 
In  the  Curtiss,  which  has  a  lifting  capacity  of  2l/2 
pounds  per  square  foot,  the  engine  is  of  50  horsepower. 
This  is  another  of  the  peculiarities  of  aerial  construction 
and  navigation.  Here  we  have  a  gain  of  */J  pound  in 
weight-lifting  capacity  with  an  expenditure  of  double 
the  horsepower.  It  is  this  feature  which  enables  Curtiss 


Curtis  Glider,  from   Which  He  Developed  Aeroplane. 

to  get  along  with  a  smaller  surface  area  of  supporting 
planes  at  the  expense  of  a  big  increase  in  engine  power. 

Proper  Weight   of   Machine. 

As  a  general  proposition  the  most  satisfactory  ma- 
chine for  amateur  purposes  will  be  found  to  be  one  with 
a  total  weight-sustaining  power  of  about  1,200  pounds. 
Deducting  170  pounds  as  the  weight  of  the  operator, 
this  will  leave  1,030  pounds  for  the  complete  motor- 
equipped  machine,  and  it  should  be  easy  to  construct  one 
within  this  limit.  This  implies,  of  course,  that  due  care 


CONSTRUCTION   AND   OPERATION 


107 


will  be  taken  to  eliminate  all  superfluous  weight  by  using 
the  lightest  material  compatible  with  strength  and  safety. 
This  plan  will  admit  of  686  pounds  weight  in  the 
frame  work,  coverings,  etc.,  and  344  for  the  motor, 
propeller,  etc.,  which  will  be  ample.  Just  how  to  dis- 
tribute the  weight  of  the  planes  is  a  matter  which  must 
be  left  to  the  ingenuity  of  the  builder. 


Comparison  of  Wing  Surface  of  Albatross  and  Vulture. 


Comparison  of  Bird  Power. 

There  is  an  interesting  study  in  the  accompanying 
illustration.  Note  that  the  surface  area  of  the  albatross 
is  much  smaller  than  that  of  the  vulture,  although  the 
wing  spread  is  about  the  same.  Despite  this  the  alba- 
tross accomplishes  fully  as  much  in  the  way  of  flight 
and  soaring  as  the  vulture.  Why?  Because  the  alba- 


108  FLYING   MACHINES: 

tross  is  quicker  and  more  powerful  in  action.  It  is 
the  application  of  this  same  principle  in  flying  machines 
which  enables  those  of  great  speed  and  power  to  get 
along  with  less  supporting  surface  than  those  of  slower 
movement. 

Measurements  of  Curtiss  Machine. 

Some  idea  of  framework  proportion  may  be  had  from 
the  following  description  of  the  Curtiss  machine.  The 
main  planes  have  a  spread  (width)  of  29  feet,  and  are 
4J/2  feet  deep.  The  front  double  surface  horizontal  rud- 
der is  6x2  feet,  with  an  area  of  24  square  feet.  To  the 
rear  of  the  main  planes  is  a  single  surface  horizontal 
plane  6x2  feet,  with  an  area  of  12  square  feet.  In  con- 
nection with  this  is  a  vertical  rudder  2^2  feet  square. 
Two  movable  ailerons,  or  balancing  planes,  are  placed 
at  the  extreme  ends  of  the  upper  planes.  These  are  6x2 
feet,  and  have  a  combined  area  of  24  square  feet.  There 
is  also  a  triangular  shaped  vertical  steadying  surface  in 
connection  with  the  front  rudder. 

Thus  we  have  a  total  of  195  square  feet,  but  as  the 
official  figures  are  258,  and  the  size  of  the  triangular- 
shaped  steadying  surface  is  unknown,  we  must  take  it 
for  granted  that  this  makes  up  the  difference.  In  the 
matter  of  proportion  the  horizontal  double-plane  rudder 
is  about  one-tenth  the  size  of  the  main  plane,  count- 
ing the  surface  area  of  only  one  plane,  the  vertical  rud- 
der one-fortieth,  and  the  ailerons  one-twentieth. 


CHAPTER    XI. 


PLANE   AND   RUDDER  CONTROL. 

Having  constructed  and  equipped  your  machine,  the 
next  thing  is  to  decide  upon  the  method  of  controlling 
the  various  rudders  and  auxiliary  planes  by  which  the 
direction  and  equilibrium  and  ascending  and  descending 
of  the  machine  are  governed. 

The  operator  must  be  in  position  to  shift  instantane- 


OPCR*TES    REAR    R.UDDER 
AND    WARPS     PLANES 

\  I  M  E 


>^  CHAIN  IS) 

How  the  Wrights  Control  Their  Machine. 

ously  the  position  of  rudders  and  planes,  and  also  to  con- 
trol the  action  of  the  motor.  This  latter  is  supposed  to 
work  automatically  and  as  a  general  thing  does  so  with 
entire  satisfaction,  but  there  are  times  when  the  supply 
of  gasolene  must  be  regulated,  and  similar  things  done. 
Airship  navigation  calls  for  quick  action,  and  for  this 

109 


110  FLYING   MACHINES: 

reason  the  matter  of  control  is  an  important  one — it  is 
more  than  important;  it  is  vital. 

Several  Methods  of  Control. 

Some  aviators  use  a  steering  wheel  somewhat  after 
the  style  of  that  used  in  automobiles,  and  by  this  not 
only  manipulate  the  rudder  planes,  but  also  the  flow  of 
gasolene.  Others  employ  foot  levers,  and  still  others, 
like  the  Wrights,  depend  upon  hand  levers. 

Curtiss  steers  his  aeroplane  by  means  of  a  wheel,  but 
secures  the  desired  stabilizing  effect  with  an  ingenious 
jointed  chair-back.  This  is  so  arranged  that  by  leaning 
toward  the  high  point  of  his  wing  planes  the  aeroplane 
is  restored  to  an  even  keel.  The  steering  post  of  the 
wheel  is  movable  backward  and  forward,  and  by  this 
motion  elevation  is  obtained. 

The  Wrights  for  some  time  used  two  hand  levers,  one 
to  steer  by  and  warp  the  flexible  tips  of  the  planes,  the 
other  to  secure  elevation.  They  have  now  consolidated 
all  the  functions  in  one  lever.  Bleriot  also  uses  the 
single  lever  control. 

Farman  employs  a  lever  to  actuate  the  rudders,  but 
manipulates  the  balancing  planes  by  foot  levers. 

Santos-Dumont  uses  two  hand  levers  with  which  to 
steer  and  elevate,  but  manipulates  the  planes  by  means 
of  an  attachment  to  the  back  of  his  outer  coat.  (See  il- 
lustration, page  in). 

Connection  With  the  Levers. 

No  matter  which  particular  method  is  employed,  the 
connection  between  the  levers  and  the  object  to  be  ma- 
nipulated is  almost  invariably  by  wire.  For  instance,  from 
the  steering  levers  (or  lever)  two  wires  connect  with  op- 
posite sides  of  the  rudder.  As  a  lever  is  moved  so  as  to 
draw  in  the  right-hand  wire  the  rudder  is  drawn  to  the 


CONSTRUCTION   AND   OPERATION  111 

right  and  vice  versa.  The  operation  is  exactly  the  same 
as  in  steering  a  boat.  It  is  the  same  way  in  changing 
the  position  of  the  balancing  planes.  A  movement  of 
the  hands  or  feet  and  the  machine  has  changed  its 
course,  or,  if  the  equilibrium  is  threatened,  is  back  on 
an  even  keel. 

Simple  as  this   seems  it  calls  for  a  cool  head,   quick 


Device  on  Back  of  Santos-Dumont's  Shirt. 

Wires  run  from  this  in  both  directions  so  the  auxiliary  planes 
may  be  manipulated  by  a  mere  movement  of  the  body  to  the  right 
or  left. 

eye,  and  steady  hand.     The  least  hesitation  or  a  false 
movement,  and  both  aviator  and  craft  are  in  danger. 

Which   Method   is   Best? 

It  would  be  a  bold  man  who  would  attempt  to  pick 
out  any  one  of  these  methods  of  control  and  say  it  was 
better  than  the  others.  As  in  other  sections  of  aeroplane 
mechanism  each  method  has  its  advocates  who  dwell 
learnedly  upon  its  advantages,  but  the  fact  remains  that 
all  the  various  plans  work  well  .and  give  satisfaction. 


112 


FLYING   MACHINES. 


13 


o    fa-§ 


J_,         rO  03 


H    ^ 


a  02 


ffl 


•a     s 


03 


CONSTRUCTION  AND   OPERATION  113 

What  the  novice  is  interested  in  knowing-  is  how  the 
control  is  effected,  and  whether  he  has  become  proficient 
enough  in  his  manipulation  of  it  to  be  absolutely  de- 
pendable in  time  of  emergency.  No  amateur  should  at- 
tempt a  flight  alone,  until  he  has  thoroughly  mastered 
the  steering  and  plane  control.  If  the  services  and  ad- 


System  of  Control  on  Farman  Machine. 

vice  of  an  experienced  aviator  are  not  to  be  had  the 
novice  should  mount  his  machine  on  some  suitable  sup- 
ports so  it  will  be  well  clear  of  the  ground,  and,  getting 
into  the  operator's  seat,  proceed  to  make  himself  well 
acquainted  with  the  operation  of  the  steering  wheel  and 
levers. 

Some  Things  to  Be  Learned. 

He  will  soon  learn  that  certain  movements  of  the 
steering  gear  produce  certain  effects  on  the  rudders.  If, 
for  instance,  his  machine  is  equipped  with  a  steering 
wheel,  he  will  find  that  turning  the  wheel  to  the  right 
turns  the  aeroplane  in  the  same  direction,  because  the 


114 


FLYING   MACHINES: 


rudder  is  brought  around  to  the  left.  In  the  same  way 
he  will  learn  that  a  given  movement  of  the  lever  throws 
the  forward  edge  of  the  main  plane  upward,  and  that  the 
machine,  getting  the  impetus  of  the  wind  under  the  con- 
cave surfaces  of  the  planes,  will  ascend.  In  the  same 
way  it  will  quickly  become  apparent  to  him  that  an  op- 
posite movement  of  the  lever  will  produce  an  opposite 
effect — the  forward  edges  of  the  planes  will  be  lowered, 
the  air  will  be  "spilled"  out  to  the  rear,  and  the  machine 
will  descend. 

The  time  expended  in  these  preliminary  lessons  will 
be  well  spent.  It  would  be  an  act  of  folly  to  attempt  to 
actually  sail  the  craft  without  them. 


Control    System   on   Voisin    Machine. 


CHAPTER    XII. 


HOW  TO  USE  THE  MACHINE. 

It  is  a  mistaken  idea  that  flying  machines  must  be 
operated  at  extreme  altitudes.  True,  under  the  impetus 
of  handsome  prizes,  and  the  incentive  to  advance  scien- 
tific knowledge,  professional  aviators  have  ascended  to 


Operator's  Weight  in  Center  Keeps  Machine  Level. 

considerable  heights,  flights  at  from  500  to  1,500  feet  be- 
ing now  common  with  such  experts  as  Farman,  Bleriot, 
Latham,  Paulhan,  Wright  and  Curtiss.  The  altitude 
record  at  this  time  is  about  4,165  feet,  held  by  Paulhan. 
One  of  the  instructions  given  by  experienced  aviators 
to  pupils,  and  fojr  which  they  insist  upon  implicit  obey- 

115 


116  FLYING   MACHINES: 

ance,  is :  "If  your  machine  gets  more  than  30  feet  high, 
or  comes  closer  to  the  ground  than  6  feet,  descend  at 
once."  Such  men  as  Wright  and  Curtiss  will  not  tol- 
erate a  violation  of  this  rule.  If  their  instructions  are 
not  strictly  complied  with  they  decline  to  give  the  of- 
fender further  lessons. 

Why  This  Rule  Prevails. 

There  is  good  reason  for  this  precaution.  The  higher 
the  altitude  the  more  rarefied  (thinner)  becomes  the  air, 
and  the  less  sustaining  power  it  has.  Consequently  the 
more  difficult  it  becomes  to  keep  in  suspension  a  given 
weight.  When  sailing  within  30  feet  of  the  ground  sus- 
tentation  is  comparatively  easy  and,  should  a  fall  occur, 
the  results  are  not  likely  to  be  serious.  On  the  other 
hand,  sailing  too  near  the  ground  is  almost  as  objection- 
able in  many  ways  as  getting  up  too  high.  If  the  craft 
is  navigated  too  close  to  the  ground  trees,  shrubs,  fences 
and  other  obstructions  are  liable  to  be  encountered. 
There  is  also  the  handicap  of  contrary  air  currents 
diverted  by  the  obstructions  referred  to,  and  which  will 
be  explained  more  fully  further  on. 

How  to  Make  a  Start. 

Taking  it  for  granted  that  the  beginner  has  familiarized 
himself  with  the  manipulation  of  the  machine,  and  es- 
pecially the  control  mechanism,  the  next  thing  in  order 
is  an  actual  flight.  It  is  probable  that  his  machine  will 
be  equipped  with  a  wheeled  alighting  gear,  as  the  skids 
used  by  the  Wrights  necessitate  the  use  of  a  special 
starting  track.  In  this  respect  the  wheeled  machine  is 
much  easier  to  handle  so  far  as  novices  are  concerned 
as  it  may  be  easily  rolled  to  the  trial  grounds.  This, 
as  in  the  case  of  the  initial  experiments,  should  be  a 
clear,  reasonably  level  place,  free  from  trees,  fences, 


CONSTRUCTION  AND    OPERATION  117 

rocks  and  similar  obstructions  with  which  there  may  be 
danger  of  colliding. 

The  beginner  will  need  the  assistance  of  three  men. 
One  of  these  should  take  his  position  in  the  rear  of  the 
machine,  and  one  at  each  end.  On  reaching  the  trial 
ground  the  aviator  takes  his  seat  in  the  machine  and, 
while  the  men  at  the  ends  keep  it  steady  the  one  in  the 
rear  pushes  it  along  briskly  for  some  distance.  In  the 


Operator's  Weight  Back  of  Center  Tilts  Planes  Upward. 

meantime  the  aviator  has  started  his  motor.  Like  the 
glider  the  flying  machine,  in  order  to  accomplish  the 
desired  results,  should  be  headed  into  the  wind. 

When  the  Machine  Rises. 

Under  the  impulse  of  the  pushing  movement,  and  as- 
sisted by  the  motor  action,  the  machine  will  gradually 
rise  from  the  ground — provided  it  has  been  properly  pro- 
portioned and  put  together,  and  everything  is  in  work- 
ing order.  This  is  the  time  when  the  aviator  requires 
a  cool  head.  At  a  modest  distance  from  the  ground  use 


118  FLYING  MACHINES: 

the  control  lever  to  bring  the  machine  on  a  horizontal 
level  and  overcome  the  tendency  to  rise.  The  exact 
manipulation  of  this  lever  depends  upon  the  method  of 
control  adopted,  and  with  this  the  aviator  is  supposed 
to  have  thoroughly  familiarized  himself  as  previously 
advised  in  Chapter  XL 

It  is  at  this  juncture  that  the  operator  must  act 
promptly,  but  with  the  perfect  composure  begotten  of 
confidence.  One  of  the  great  drawbacks  in  aviation  by 
novices  is  the  tendency  to  become  rattled,  and  this  is 
much  more  prevalent  than  one  might  suppose,  even 
among  men  who,  under  other  conditions,  are  cool  and 
confident  in  their  actions. 

There  is  something  in  the  sensation  of  being  suddenly 
lifted  from  the  ground,  and  suspended  in  the  air  that  is 
disconcerting  at  the  start,  but  this  will  soon  wear  off  if 
the  experimenter  will  keep  cool.  A  few  successful  flights 
no  matter  how  short  they  may  be,  will  put  a  lot  of 
confidence  into  him. 

Make  Your  Flights  Short. 

Be  modest  in  your  initial  flights.  Don't  attempt  to 
match  the  records  of  experienced  men  who  have  devoted 
years  to  mastering  the  details  of  aviation.  Paulhan, 
Farman,  Bleriot,  Wright,  Curtiss,  and  all  the  rest  of 
them  began,  and  practiced  for  years,  in  the  manner  here 
described,  being  content  to  make  just  a  little  advance- 
ment at  each  attempt.  A  flight  of  150  feet,  cleanly  and 
safely  made,  is  better  as  a  beginning  than  one  of  400 
yards  full  of  bungling  mishaps. 

And  yet  these  latter  have  their  uses,  provided  the 
operator  is  of  a  discerning  mind  and  can  take  advantage 
of  them  as  object  lessons.  But,  it  is  not  well  to  invite 
them.  They  will  occur  frequently  enough  under  the 
most  favorable  conditions,  and  it  is  best  to  have  them 


CONSTRUCTION   AND   OPERATION  110 

come  later  when  the  feeling  of  trepidation  and  uncer- 
tainty as  to  what  to  do  has  worn  off. 

Above  all,  don't  attempt  to  fly  too  high.  Keep  within 
a  reasonable  distance  from  the  ground — about  25  or  30 
feet.  This  advice  is  not  given  solely  to  lessen  the  risk 
of  serious  accident  in  case  of  collapse,  but  mainly  be- 
cause it  will  assist  to  instill  confidence  in  the  operator. 


Operator's  Weight  Forward  of  Center  Depresses  Planes. 

It  is  comparatively  easy  to  learn  to  swim  in  shallow 
water,  but  the  knowledge  that  one  is  tempting  death  in 
deep  water  begets  timidity. 

Preserving  the  Equilibrium. 

After  learning  how  to  start  and  stop,  to  ascend  and 
descend,  the  next  thing  to  master  is  the  art  of  preserving 
equilibrium,  the  knack  of  keeping  the  machine  perfectly 
level  in  the  air — on  an  "even  keel,"  as  a  sailor  would 
say.  This  simile  is  particularly  appropriate  as  all  avia- 
tors are  in  reality  sailors,  and  much  more  daring  ones 


120  FLYING  MACHINES: 

than  those  who  course  the  seas.  The  latter  are  in  craft 
which  are  kept  afloat  by  the  buoyancy  of  the  water, 
whether  in  motion  or  otherwise  and,  so  long  as  normal 
conditions  prevail,  will  not  sink.  Aviators  sail  the  air 
in  craft  in  which  constant  motion  must  be  maintained  in 
order  to  ensure  flotation. 

The  man  who  has  ridden  a  bicycle  or  motorcycle 
around  curves  at  anything  like  high  speed,  will  have  a 
very  good  idea  as  to  the  principle  of  maintaining  equilib- 
rium in  an  airship.  He  knows  that  in  rounding  curves 
rapidly  there  is  a  marked  tendency  to  change  the  direc- 
tion of  the  motion  which  will  result  in  an  upset  unless 
he  overcomes  it  by  an  inclination  of  his  body  in  an  op- 
posite direction.  This  is  why  we  see  racers  lean  well 
over  when  taking  the  curves.  It  simply  must  be  done 
to  preserve  the  equilibrium  and  avoid  a  spill. 

How  It  Works  In  the  Air. 

If  the  equilibrium  of  an  airship  is  disturbed  tp  an 
extent  which  completely  overcomes  the  center  of  gravity 
it  falls  according  to  the  location  of  the  displacement. 
If  this  displacement,  for  instance,  is  at  either  end  the 
apparatus  falls  endways ;  if  it  is  to  the  front  or  rear,  the 
fall  is  in  the  corresponding  direction. 

Owing  to  uncertain  air  currents — the  air  is  continually 
shifting  and  eddying,  especially  within  a  hundred  feet  or 
so  of  the  earth — the  equilibrium  of  an  airship  is  almost 
constantly  being  disturbed  to  some  extent.  Even  if  this 
disturbance  is  not  serious  enough  to  bring  on  a  fall  it 
interferes  with  the  progress  of  the  machine,  and  should 
be  overcome  at  once.  This  is  one  of  the  things  con- 
nected with  aerial  navigation  which  calls  for  prompt, 
intelligent  action. 

Frequently,  when  the  displacement  is  very  slight,  it 
may  be  overcome,  and  the  craft  immediately  righted  by 


CONSTRUCTION  AND    OPERATION 


121 


a  mere  shifting  of  the  operator's  body.  Take,  for  il- 
lustration, a  case  in  which  the  extreme  right  end  of  the 
machine  becomes  lowered  a  trifle  from  the  normal  level. 
It  is  possible  to  bring  it  back  into  proper  position  by 
leaning  over  to  the  left  far  enough  to  shift  the  weight 
to  the  counter-balancing  point.  The  same  holds  good  as 
to  minor  front  or  rear  displacements. 

When  Planes  Must  Be  Used. 

There  are  other  displacements,  however,  and  these  are 
the  most  frequent,  which  can  be  only  overcome  by  man- 


Equilibrium   Paradox   Explained. 

ipulation  of  the  stabilizing  planes.  The  method  of  pro- 
cedure depends  upon  the  form  of  machine  in  use.  The 
Wright  machine,  as  previously  explained,  is  equipped 
with  plane  ends  which  are  so  contrived  as  to  admit  of 


122  FLYING   MACHINES: 

their  being  warped  (position  changed)  by  means  of  the 
lever  control.  These  flexible  tip  planes  move  simultane- 
ously, but  in  opposite  directions.  As  those  on  one  end 
rise,  those  on  the  other  end  fall  below  the  level  of  the 
main  plane.  By  this  means  air  is  displaced  at  one  point, 
and  an  increased  amount  secured  in  another. 

This  may  seem  like  a  complicated  system,  but  its 
workings  are  simple  when  once  understood.  It  is  by 
the  manipulation  or  warping  of  these  flexible  tips  that 
transverse  stability  is  maintained,  and  any  tendency  to 
displacement  endways  is  overcome.  Longitudinal  sta- 
bility is  governed  by  means  of  the  front  rudder. 

Stabilizing  planes  of  some  form  are  a  feature,  and  a 
necessary  feature,  on  all  flying  machines,  but  the  methods 
of  application  and  manipulation  vary  according  to  the 
individual  ideas  of  the  inventors.  They  all  tend,  how- 
ever, toward  the  same  end — the  keeping  of  the  machine 
perfectly  level  when  being  navigated  in  the  air. 

When  to  Make  a  Flight. 

A  beginner  should  never  attempt  to  make  a  flight 
when  a  strong  wind  is  blowing.  The  fiercer  the  wind, 
the  more  likely  it  is  to  be  gusty  and  uncertain,  and  the 
more  difficult  it  will  be  to  control  the  machine.  Even 
the  most  experienced  and  daring  of  aviators  find  there 
is  a  limit  to  wind  speed  against  which  they  dare  not 
compete.  This  is  not  because  they  lack  courage,  but 
have  the  sense  to  realize  that  it  would  be  silly  and  use- 
less. 

The  novice  will  find  a  comparatively  still  day,  or  one 
when  the  wind  is  blowing  at  not  to  exceed  15  miles  an 
hour,  the  best  for  his  experiments.  The  machine  will  be 
more  easily  controlled,  the  trip  will  be  safer,  and  also 
cheaper  as  the  consumption  of  fuel  increases  with  the 
speed  of  the  wind  against  which  the  aeroplane  is  forced. 


CHAPTER  XIII. 

PECULIARITIES  OF  AIRSHIP  POWER. 

As  a  general  proposition  it  takes  much  more  power  to 
propel  an  airship  a  given  number  of  miles  in  a  certain 
time  than  it  does  an  automobile  carrying  a  far  heavier 
load.  Automobiles  with  a  gross  load  of  4,000  pounds, 
and  equipped  with  engines  of  30  horsepower,  have  trav- 
elled considerable  distances  at  the  rate  of  50  miles  an 
hour.  This  is  an  equivalent  of  about  134  pounds  per 
horsepower.  For  an  average  modern  flying  machine, 
with  a  total  load,  machine  and  passengers,  of  1,200 
pounds,  and  equipped  with  a  5o-horsepower  engine,  50 
miles  an  hour  is  the  maximum.  Here  we  have  the  equiv- 
alent of  exactly  24  pounds  per  horsepower.  Why  this 
great  difference? 

No  less  an  authority  than  Mr.  Octave  Chanute  answers 
the  question  in  a  plain,  easily  understood  manner.  He 
says : 

"In  the  case  of  an  automobile  the  ground  furnishes  a 
stable  support;  in  the  case  of  a  flying  machine  the  engine 
must  furnish  the  support  and  also  velocity  by  which  the 
apparatus  is  sustained  in  the  air." 

Pressure  of  the  Wind. 

Air  pressure  is  a  big  factor  in  the  matter  of  aeroplane 
horsepower.  Allowing  that  a  dead  calm  exists,  a  body 
moving  in  the  atmosphere  creates  more  or  less  resist- 
ance. The  faster  it  moves,  the  greater  is  this  resistance. 
Moving  at  the  rate  of  60  miles  an  hour  the  resistance, 

123 


124  FLYING  MACHINES: 

or  wind  pressure,  is  approximately  50  pounds  to  the 
square  foot  of  surface  presented.  If  the  moving  object 
is  advancing  at  a  right  angle  to  the  wind  the  following 
table  will  give  the  horsepower  effect  of  the  resistance 
per  square  foot  of  surface  at  various  speeds. 

Horse  Power 
Miles  per  Hour  per  sq.  foot 

10  0.013 

15  0.044 

20  0.105 

25  0.205 

30  0.354 

40  0.84 

50  1.64 

60  2.83 

80  6.72 

ioo  13.12 

While  the  pressure  per  square  foot  at  60  miles  an  hour, 
is  only  1.64. horsepower,  at  ioo  miles,  less  than  double 
the  speed,  it  has  increased  to  13.12  horsepower,  or  ex- 
actly eight  times  as  much.  In  other  words  the  pressure 
of  the  wind  increases  with  the  square  of  the  velocity. 
Wind  at  10  miles  an  hour  has  four  times  more  pressure 
than  wind  at  5  miles  an  hour. 

How  to  Determine  Upon  Power. 

This  element  of  air  resistance  must  be  taken  into  con- 
sideration in  determining  the  engine  horsepower  re- 
quired. When  the  machine  is  under  headway  sufficient 
to  raise  it  from  the  ground  (about  20  miles  an  hour), 
each  square  foot  of  surface  resistance,  will  require  nearly 
nine-tenths  of  a  horsepower  to  overcome  the  wind  pres- 
sure, and  propel  the  machine  through  the  air.  As 
shown  in  the  table  the  ratio  of  power  required  increases 


CONSTRUCTION  AND   OPERATION  125 

rapidly  as  the  speed  increases  until  at  60  miles  an  hour 
approximately  3  horsepower  is  needed. 

In  a  machine  like  the  Curtiss  the  area  of  wind-exposed 
surface  is  about  15  square  feet.  On  the  basis  of  this  re- 
sistance moving  the  machine  at  40  miles  an  hour  would 
require  12  horsepower.  This  computation  covers  only 


!*%WW1-' 

"r 


One  of  the  Early  Multiplane   Gliders. 

the  machine's  power  to  overcome  resistance.  It  does 
not  cover  the  power  exerted  in  propelling  the  machine 
forward  after  the  air  pressure  is  overcome.  To  meet 
this  important  requirement  Mr.  Curtiss  finds  it  neces- 
sary to  use  a  5o-horsepower  engine.  Of  this  power,  as 
has  been  already  stated,  12  horsepower  is  consumed 
in  meeting  the  wind  pressure,  leaving  38  horsepower 
for  the  purpose  of  making  progress. 

The  flying  machine  must  move  faster  than  the  air  to 


126  FLYING   MACHINES: 

which  it  is  opposed.  Unless  it  does  this  there  can  be  no 
direct  progress.  If  the  two  forces  are  equal  there  is  no 
straight-ahead  advancement.  Take,  for  sake  of  illustra- 
tion, a  case  in  which  an  aeroplane,  which  has  developed  a 
speed  of  30  miles  an  hour,  meets  a  wind  velocity  of 
equal  force  moving  in  an  opposite  direction.  What  is 
the  result?  There  can  be  no  advance  because  it  is  a 
contest  between  two  evenly  matched  forces.  The  aero- 
plane stands  still.*)  The  only  way  to  get  out  of  the  diffi- 
culty is  for  the  operator  to  resort  to  "tacking,"  just  as 
a  ship  captain  does  when  he  is  caught  in  a  similar  pre- 
dicament. 

Take  another  case.  An  aeroplane,  capable  of  making 
50  miles  an  hour  in  a  calm,  is  met  by  a  head  wind  of  25 
miles  an  hour.  How  much  progress  does  the  aeroplane 
make?  Obviously  it  is  25  miles  an  hour  over  the  ground. 

Put  the  proposition  in  still  another  way.  If  the  wind 
is  blowing  harder  than  it  is  possible  for  the  engine  power 
to  overcome,  the  machine  will  be  forced  backward. 

Wind   Pressure   a   Necessity. 

While  all  this  is  true,  the  fact  remains  that  wind 
pressure,  up  to  a  certain  stage,  is  an  absolute  necessity 
in  aerial  navigation.  The  atmosphere  itself  has  very 
little  real  supporting  power,  especially  if  inactive.  If 
a  body  heavier  than  air  is  to  remain  afloat  it  must  move 
rapidly  while  in  suspension. 

One  of  the  best  illustrations  of  this  is  to  be  found  in 
skating  over  thin  ice.  Every  school  boy  knows  that  if 
he  moves  with  speed  he  may  skate  or  glide  in  safety 
across  a  thin  sheet  of  ice  that  would  not  begin  to  bear 
his  weight  if  he  were  standing  still.  Exactly  the  same 
proposition  obtains  in  the  case  of  the  flying  machine. 

The  non-technical  reason  why  the  support  of  the  ma- 
chine becomes  easier  as  the  speed  increases  is  that  the 


CONSTRUCTION   AND    OPERATION 


127 


sustaining  power  of  the  atmosphere  increases  with  the 
resistance,  and  the  speed  with  which  the  object  is  mov- 
ing increases  this  resistance.  With  a  velocity  of  12  miles 
an  hour  the  weight  of  the  machine  is  practically  reduced 
by  230  pounds.  Thus,  if  under  a  condition  of  absolute 
calm  it  were  possible  to  sustain  a  weight  of  770  pounds, 
the  same  atmosphere  would  sustain  a  weight  of  1,000 
pounds  moving  at  a  speed  of  12  miles  an  hour.  This 


Sccxle     fut 


Huffaker's  Model  Bird  for  Soaring  Experiments. 

sustaining  power  increases  rapidly  as  the  speed  increases. 
While  at  12  miles  the  sustaining  power  is  figured  at 
230  pounds,  at  24  miles  it  is  four  times  as  great,  or  920 
pounds. 

Supporting  Area  of  Birds. 

One  of  the  things  which  all  producing  aviators  seek 
to  copy  is  the  motive  power  of  birds,  particularly  in  their 
relation  to  the  area  of  support.  Close  investigation  has 
established  the  fact  that  the  larger  the  bird  the  less  is 
the  relative  area  of  support  required  to  secure  a  given 
result.  This  is  shown  in  the  following  table : 


128  FLYING   MACHINES: 

Support- 
Weight  Surface  Horse  ing  area 
Bird                        in  Ibs.           in  sq.  feet                 power  per  Ib. 

Pigeon    ..- i.oo  0.7  0.012  0.7 

Wild   Goose    ....   9.00  2.65  0.026  0.2833 

Buzzard    5.00  5.03  0.015  1.06 

Condor    ...17.00  9.85  0.043  °-57 

So  far  as  known  the  condor  is  the  largest  of  modern 
birds.  It  has  a  wing  stretch  of  10  feet  from  tip  to  tip,  a 
supporting  area  of  about  10  square  feet,  and  weighs  17 
pounds.  It  is  capable  of  exerting  perhaps  1-30  horse- 
power. (These  figures  are,  of  course,  approximate.) 
Comparing  the  condor  with  the  buzzard  with  a  wing 
stretch  of  6  feet,  supporting  area  of  5  square  feet,  and  a 
little  over  i-ioo  horsepower,  it  may  be  seen  that,  broadly 
speaking,  the  larger  the  bird  the  less  surface  area  (rel- 
atively) is  nee'ded  for  its  support  in  the  air. 

Comparison  With  Aeroplanes. 

If  we  compare  the  bird  figures  with  those  made  pos- 
sible by  the  development  of  the  aeroplane  it  will  be 
readily  seen  that  man  has  made  a  wonderful  advance  in 
imitating  the  results  produced  by  nature.  Here  are  the 
figures : 

Support  - 

Weight  Surface  Horse  ing  area 

Machine  in  Ibs.  in  sq.  feet  power  per  Ib. 

Santos-Dumont   ...  350  110.00  30  0.314 

Bleriot    700  150.00  25  0.214 

Antoinette    1,200  538.00  50  0.448 

Curtiss    700  258.00  60  0.368 

Wright  *i,ioo  538.00  25  0.489 

Farman    1,200  430.00  50  0.358 

Voisin    1,200  538.00  50  0.448 


*The  "Wrights'   new  machine  weighs   only  900  pounds. 

While  the  average  supporting  surface  is  in  favor  of 


CONSTRUCTION   AND    OPERATION 


129 


the  aeroplane,  this  is  more  than  overbalanced  by  the 
greater  amount  of  horsepower  required  for  the  weight 
lifted.  The  average  supporting  surface  in  birds  is  about 
three-quarters  of  a  square  foot  per  pound.  In  the  aver- 
age aeroplane  it  is  about  one-half  square  foot  per  pound. 
On  the  other  hand  the  average  aeroplane  has  a  lifting 
capacity  of  24  pounds  per  horsepower,  while  the  buzzard, 
for  instance,  lifts  5  pounds  with  15-100  of  a  horsepower. 
If  the  Wright  machine — which  has  a  lifting  power  of  50 


Other  Parts  of  Huffaker's  Bird  Model. 

pounds  per  horsepower — should  be  alone  considered  the 
showing  would  be  much  more  favorable  to  the  aero- 
plane, but  it  would  not  be  a  fair  comparison. 

More  Surface,  Less  Power. 

Broadly  speaking,  the  larger  the  supporting  area  the 
less  will  be  the  power  required.  Wright,  by  the  use  of 
538  square  feet  of  supporting  surface,  gets  along  with  an 
engine  of  25  horsepower.  Curtiss,  who  uses  only  258 
square  feet  of  surface,  finds  an  engine  of  50  horsepower 


130  FLYING   MACHINES: 

is  needed.  Other  things,  such  as  frame,  etc.,  being  equal, 
it  stands  to  reason  that  a  reduction  in  the  area  of  sup- 
porting surface  will  correspondingly  reduce  the  weight 
of  the  machine.  Thus  we  have  the  Curtiss  machine  with 
its  258  square  feet  of  surface,  weighing  only  600  pounds 
(.without  operator),  but  requiring  double  the  horsepower 
of  the  Wright  machine  with  538  square  feet  of  surface 
and  weighing  1,100  pounds.  This  demonstrates  in  a 
forceful  way  the  proposition  that  the  larger  the  surface 
the  less  power  will  be  needed. 

But  there  is  a  limit,  on  account  of  its  bulk  and  awk- 
wardness in  handling,  beyond  which  the  surface  area 
cannot  be  enlarged.  Otherwise  it  might  be  possible  to 
equip  and  operate  aeroplanes  satisfactorily  with  engines 
of  15  horsepower,  or  even  less. 

The  Fuel  Consumption  Problem. 

Fuel  consumption  is  a  prime  factor  in  the  production 
of  engine  power.  The  veriest  mechanical  tyro  knows  in 
a  general  way  that  the  more  power  is  secured  the  more 
fuel  must  be  consumed,  allowing  that  there  is  no  differ- 
ence in  the  power-producing  qualities  of  the  material 
used.  But  few  of  us  understand  just  what  the  ratio  of 
increase  is,  or  how  it  is  caused.  This  proposition  is  one 
of  keen  interest  in  connection  with  aviation. 

Let  us  cite  a  problem  which  will  illustrate  the  point 
quoted :  Allowing  that  it  takes  a  given  amount  of  gaso- 
lene to  propel  a  flying  machine  a  given  distance,  half  the 
way  with  the  wind,  and  half  against  it,  the  wind  blow- 
ing at  one-half  the  speed  of  the  machine,  what  will  be 
the  increase  in  fuel  consumption? 

Increase  of  Thirty  Per  Cent 

On  the  face  of  it  there  would  seem  to  be  no  call  for 
an  increase  as  the  resistance  met  when  going  against  the 


CONSTRUCTION  AND   OPERATION 


131 


132 


FLYING   MACHINES: 


wind  is  apparently  offset  by  the  propulsive  force  of  the 
wind  when  the  machine  is  travelling  with  it.  This,  how- 
ever, is  called  faulty  reasoning.  The  increase  in  fuel 
consumption,  as  figured  by  Mr.  F.  W.  Lanchester,  of  the 
Royal  Society  of  Arts,  will  be  fully  30  per  cent  over 
the  amount  required  for  a  similar  operation  of  the  ma- 
chine in  still  air.  If  the  journey  should  be  made  at  right 
angles  to  the  wind  under  the  same  conditions  the  in- 
crease would  be  15  per  cent. 

In  other  words  Mr.  Lanchester  maintains  that  the  work 
done  by  the  motor  in  making  headway  against  the  wind 
for  a  certain  distance  calls  for  more  engine  energy,  and 
consequently  more  fuel  by  30  per  cent,  than  is  saved  by 
the  helping  force  of  the  wind  on  the  return  journey. 


Front  View  of  New  Aerodrome. 

For  explanation  of  figures  see  cut  on  page  131. 


CHAPTER  XIV. 


ABOUT  WIND  CURRENTS,  ETC. 

One  of  the  first  difficulties  which  the  novice  will  en- 
counter is  the  uncertainty  of  the  wind  currents.  With  a 
low  velocity  the  wind,  some  distance  away  from  the 
ground,  is  ordinarily  steady.  As  the  velocity  increases, 


How  Birds  Change  Direction  of  Flight. 

however,  the  wind  generally  becomes  gusty  and  fitful 
in  its  action.  This,  it  should  be  remembered,  does  not 
refer  to  the  velocity  of  the  machine,  but  to  that  of  the 
air  itself. 

In  this  connection  Mr.  Arthur  T.  Atherholt,  president 
of  the  Aero  Club  of  Pennsylvania,  in  addressing  the 
Boston  Society  of  Scientific  Research,  said : 

"Probably  the  whirlpools  of  Niagara  contain  no  more 
erratic  currents  than  the  strata  of  air  which  is  now  im- 

133 


134  FLYING   MACHINES: 

mediately  above  us,   a   fact  hard  to   realize  on   account 
of  its  invisibility." 

Changes  In  Wind  Currents. 

While  Mr.  Atherholt's  experience  has  been  mainly 
with  balloons  it  is  all  the  more  valuable  on  this  account, 
as  the  balloons  were  at  the  mercy  of  the  wind  and  their 
varying  directions  afforded  an  indisputable  guide  as  to 
the  changing  course  of  the  air  currents.  In  speaking  of 
this  he  said: 

"In  the  many  trips  taken,  varying  in  distance  traversed 
from  twenty-five  to  900  miles,  it  was  never  possible 
except  in  one  instance  to  maintain  a  straight  course. 
These  uncertain  currents  were  most  noticeable  in  the 
Gordon-Bennett  race  from  St.  Louis  in  1907.  Of  the 
nine  aerostats  competing  in  that  event,  eight  covered  a 
more  or  less  direct  course  due  east  and  southeast,  where- 
as the  writer,  with  Major  Henry  B.  Hersey,  first  started 
northwest,  then  north,  northeast,  east,  east  by  south,  and 
when  over  the  center  of  Lake  Erie  were  again  blown 
northwest  notwithstanding  that  more  favorable  winds 
were  sought  for  at  altitudes  varying  from  100  to  3,000 
meters,  necessitating  a  finish  in  Canada  nearly  northeast 
of  the  starting  point. 

"These  nine  balloons,  making  landings  extending  from 
Lake  Ontario,  Canada,  to  Virginia,  all  started  from  one 
point  within  the  same  hour. 

"The  single  exception  to  these  roving  currents  oc- 
curred on  October  2ist,  of  last  year  (1909)  when,  start- 
ing from  Philadelphia,  the  wind  shifted  more  than  eight 
degrees,  the  greatest  variation  being  at  the  lowest  alti- 
tudes, yet  at  no  time  was  a  height  of  over  a  mile  reached. 

"Throughout  the  entire  day  the  sky  was  overcast,  with 
a  thermometer  varying  from  fifty-seven  degrees  at  300 
feet  to  forty-four  degrees,  Fahrenheit  at  5,000  feet,  at 


UNIVERSITY 

OF 


CONSTRUCTION   AND    OPERATION 


135 


which  altitude  the  wind  had  a  velocity  of  43  miles  an 
hour,  in  clouds  of  a  cirro-cumulus  nature,  a  landing  final- 
ly being  made  near  Tannersville,  New  York,  in  the 
Catskill  mountains,  after  a  voyage  of  five  and  one-half 
hours. 

"I  have  no  knowledge  of  a  recorded  trip  of  this  dis- 
tance and  duration,  maintained  in  practically  a  straight 
line  from  start  to  finish." 

This  wind   disturbance   is   more  noticeable   and   more 


\ 

From   Aeronautical   Annual. 

Chanute's   Multiplane   Glider,   as   Seen   from   Top. 


difficult  to  contend  with  in  a  balloon  than  in  a  flying 
machine,  owing  to  the  bulk  and  unwieldy  character  of 
the  former.  At  the  same  time  it  is  not  conducive  to 
pleasant,  safe  or  satisfactory  sky-sailing  in  an  aeroplane. 
This  is  not  stated  with  the  purpose  of  discouraging  avia- 
tion, but  merely  that  the  operator  may  know  what  to 
expect  and  be  prepared  to  meet  it. 


136  FLYING   MACHINES: 

Not  only  does  the  wind  change  its  horizontal  course 
abruptly  and  without  notice,  but  it  also  shifts  in  a  ver- 
tical direction,  one  second  blowing  up,  and  another 
down.  No  man  has  as  yet  fathomed  the  why  and  where- 
fore of  this  erratic  action ;  it  is  only  known  that  it  exists. 

The  most  stable  currents  will  be  found  from  50  to  100 
feet  from  the  earth,  provided  the  wind  is  not  diverted 
by  such  objects  as  trees,  rocks,  etc.  That  there  are 
equally  stable  currents  higher  up  is  true,  but  they  are 
generally  to  be  found  at  excessive  altitudes. 

How  a  Bird  Meets  Currents. 

Observe  a  bird  in  action  on  a  windy  day  and  you  will 
find  it  continually  changing  the  position  of  its  wings. 
This  is  done  to  meet  the  varying  gusts  and  eddies  of  the 
air  so  that  sustentation  may  be  maintained  and  headway 
made.  One  second  the  bird  is  bending  its  wings,  alter- 
ing the  angle  of  incidence ;  the  next  it  is  lifting  or  de- 
pressing one  wing  at  a  time.  Still  again  it  will  extend 
one  wing  tip  in  advance  of  the  other,  or  be  spreading  or 
folding,  lowering  or  raising  its  tail. 

All  these  motions  have  a  meaning,  a  purpose.  They 
assist  the  bird  in  preserving  its  equilibrium.  Without 
them  the  bird  would  be  just  as  helpless  in  the  air  as  a 
human  being  and  could  not  remain  afloat. 

When  the  wind  is  still,  or  comparatively  so,  a  bird, 
having  secured  the  desired  altitude  by  flight  at  an  angle, 
may  sail  or  soar  with  no  wing  action  beyond  an  occa- 
sional stroke  when  it  desires  to  advance.  But,  in  a 
gusty,  uncertain  wind  it  must  use  its  wings  or  alight 
somewhere. 

Trying  to  Imitate  the  Bird. 

Writing  in  Fly,  Mr.  Wrilliam  E.  White  says: 
"The  bird's  flight  suggests  a  number  of  ways  in  which 
the  equilibrium  of  a  mechanical  bird  may  be  controlled. 


CONSTRUCTION   AND    OPERATION 


137 


Each   of  these  methods   of  control   may  be   effected  by 
several  different  forms  of  mechanism. 

"Placing  the  two  wings  of  an  aeroplane  at  an  angle  of 
three  to  five  degrees  to  each  other  is  perhaps  the  oldest 
way  of  securing  lateral  balance.  This  way  readily  oc- 
curs to  anyone  who  watches  a  sea  gull  soaring.  The 
theory  of  the  dihedral  angle  is  that  when  one  wing  is 
lifted  by  a  gust  of  wind,  the  air  is  spilled  from  under  it ; 
while  the  other  wing,  being  correspondingly  depressed, 
presents  a  greater  resistance  to  the  gust  and  is  lifted 


Front  Elevation  of  Multiplane  Glider. 

restoring  the  balance.  A  fixed  angle  of  three  to  five  de- 
grees, however,  will  only  be  sufficient  for  very  light  puffs 
of  wind  and  to  mount  the  wings  so  that  the  whole  wing 
may  be  moved  to  change  the  dihedral  angle  presents 
mechanical  difficulties  which  would  be  better  avoided. 

"The  objection  of  mechanical  impracticability  applies 
to  any  plan  to  preserve  the  balance  by  shifting  weight 
or  ballast.  The  center  of  gravity  should  be  lower  than 
the  center  of  the  supporting  surfaces,  but  cannot  be 
made  much  lower.  It  is  a  common  mistake  to  assume 
that  complete  stability  will  be  secured  by  hanging  the 
center  of  gravity  very  low  on  the  principle  of  the  para- 
chute. An  aeroplane  depends  upon  rapid  horizontal  mo- 


138  FLYING   MACHINES: 

tion  for  its  support,  and  if  the  center  of  gravity  be  far 
below,  the  center  of  support,  every  change  of  speed  or 
wind  pressure  will  cause  the  machine  to  turn  about  its 
center  of  gravity,  pitching  forward  and  backward  dan- 
gerously. 

Preserving  Longitudinal  Balance. 

"The  birds  maintain  longitudinal,  or  fore  and  aft  bal- 
ance, by  elevating  or  depressing  their  tails.  Whether 
this  action  is  secured  in  an  aeroplane  by  means  of  a 
horizontal  rudder  placed  in  the  rear,  or  by  deflecting 
planes  placed  in  front  of  the  main  planes,  the  principle 
is  evidently  the  same.  A  horizontal  rudder  placed  well 
to  the  rear  as  in  the  Antoinette,  Bleriot  or  Santos-Du- 
mont  monoplanes,  will  be  very  much  safer  and  steadier 
than  the  deflecting  planes  in  front,  as  in  the  Wright  or 
Curtiss  biplanes,  but  not  so  sensitive  or  prompt  in  action. 

"The  natural  fore  and  aft  stability  is  very  much 
strengthened  by  placing  the  load  well  forward.  The 
center  of  gravity  near  the  front  and  a  tail  or  rudder 
streaming  to  the  rear  secures  stability  as  an  arrow  is 
balanced  by  the  head  and  feathering.  The  adoption  of 
this  principle  makes  it  almost  impossible  for  the  aero- 
plane to  turn  over. 

The  Matter  of  Lateral  Balance. 

"All  successful  aeroplanes  thus  far  have  maintained 
lateral  balance  by  the  principle  of  changing  the  angle 
of  incidence  of  the  wings. 

"Other  ways  of  maintaining  the  lateral  balance,  sug- 
gested by  observation  of  the  flight  of  birds  are — extend- 
ing the  wing  tips  and  spilling  the  air  through  the  pin- 
ions ;  or,  what  is  the  same  thing,  varying  the  area  of  the 
wings  at  their  extremities. 

"Extending  the  wing  tips  seems  to  be  a  simple  and 
effective  solution  of  the  problem.  The  tips  may  be  made 


CONSTRUCTION   AND    OPERATION 


139 


to  swing  outward  upon  a  vertical  axis  placed  at  the  front 
edge  of  the  main  planes;  or  they  may  be  hinged  to  the 
ends  of  the  main  plane  so  as  to  be  elevated  or  depressed 
through  suitable  connections  by  the  aviator ;  or  they  may 
be  supported  from  a  horizontal  axis  parallel  with  the 
ends  of  the  main  planes  so  that  they  may  swing  out- 
ward, the  aviator  controlling  both  tips  through  one  lever 
so  that  as  one  tip  is  extended  the  other  is  retracted. 


Side  Elevation  of  Multiplane  Glider. 

"The  elastic  wing  pinions  of  a  bird  bend  easily  before 
the  wind,  permitting  the  gusts  to  glance  off,  but  pre- 
senting always  an  even  and  efficient  curvature  to  the 
steady  currents  of  the  air." 

High  Winds  Threaten  Stability. 

To  ensure  perfect  stability,  without  control,  either  hu- 
man or  automatic,  it  is  asserted  that  the  aeroplane  must 
move  faster  than  the  wind  is  blowing.  So  long  as  the 
wind  is  blowing  at  the  rate  of  30  miles  an  hour,  and  the 
machine  is  traveling  40  or  more,  there  will  be  little  trou- 
ble as  regards  equilibrium  so  far  as  wind  disturbance 


140  FLYING   MACHINES: 

goes,  provided  the  wind  blows  evenly  and  does  not  come 
in  gusts  or  eddying  currents.  But  when  conditions  are 
reversed — when  the  machine  travels  only  30  miles  an 
hour  and  the  wind  blows  at  the  rate  of  50,  look  out  for 
loss  of  equilibrium. 

One  of  the  main  reasons  for  this  is  that  high  winds 
are  rarely  steady;  they  seldom  blow  for  any  length  of 
time  at  the  same  speed.  They  are  usually  "gusty,"  the 
gusts  being  a  momentary  movement  at  a  higher  speed. 
Tornadic  gusts  are  also  formed  by  the  meeting  of  two 
opposing  currents,  causing  a  whirling  motion,  which 
makes  stability  uncertain.  Besides,  it  is  not  unusual 
for  wind  of  high  speed  to  suddenly  change  its  direction 
without  warning. 

Trouble   With   Vertical   Columns. 

Vertical  currents — columns  of  ascending  air — are  fre- 
quently encountered  in  unexpected  places  and  have  more 
or  less  tendency,  according  to  their  strength,  to  make 
it  difficult  to  keep  the  machine  within  a  reasonable  dis- 
tance from  the  ground. 

These  vertical  currents  are  most  generally  noticeable 
in  the  vicinity  of  steep  cliffs,  or  deep  ravines.  In  such 
instances  they  are  usually  of  considerable  strength,  be- 
ing caused  by  the  deflection  of  strong  winds  blowing 
against  the  face  of  the  cliffs.  This  deflection  exerts  a 
back  pressure  which  is  felt  quite  a  distance  away  from 
the  point  of  origin,  so  that  the  vertical  current  exerts  an 
influence  in  forcing  the  machine  upward  long  before  the 
cliff  is  reached. 


CHAPTER  XV. 

THE  ELEMENT  OF  DANGER. 

That  there  is  an  element  of  danger  in  aviation  is  un- 
deniable, but  it  is  nowhere  so  great  as  the  public 
imagines.  Men  are  killed  and  injured  in  the  operation 
of  flying  machines  just  as  they  are  killed  and  injured  in 
the  operation  of  railways.  Considering  the  character  of 
aviation  the  percentage  of  casualties  is  surprisingly 
small. 

This  is  because  the  results  following  a  collapse  in  the 
air  are  very  much  different  from  what  might  be  imagined. 
Instead  of  dropping  to  the  ground  like  a  bullet  an  aero- 
plane, under  ordinary  conditions  will,  when  anything 
goes  wrong,  sail  gently  downward  like  a  parachute,  par- 
ticularly if  the  operator  is  cool-headed  and  nervy  enough 
to  so  manipulate  the  apparatus  as  to  preserve  its  equili- 
brium and  keep  the  machine  on  an  even  keel. 

Two  Fields  of  Safety. 

At  least  one  prominent  aviator  has  declared  that  there 
are  two  fields  of  safety — one  close  to  the  ground,  and 
the  other  well  up  in  the  air.  In  the  first-named  the  fall 
will  be  a  slight  one  with  little  chance  of  the  operator 
being  seriously  hurt.  From  the  field  of  high  altitude  the 
the  descent  will  be  gradual,  as  a  rule,  the  planes  of  the 
machine  serving  to  break  the  force  of  the  fall.  With  a 
cool-headed  operator  in  control  the  aeroplane  may  be 
even  guided  at  an  angle  (about  i  to  8)  in  its  descent  so 

141 


142  FLYING   MACHINES: 

as  to  touch  the  ground  with  a  gliding  motion  and  with 
a  minimum  of  impact. 

Such  an  experience,  of  course,  is  far  from  pleasant, 
but  it  is  by  no  means  so  dangerous  as  might  appear. 
There  is  more  real  danger  in  falling  from  an  elevation 
of  75  or  100  feet  than  there  is  from  1,000  feet,  as  in  the 
former  case  there  is  no  chance  for  the  machine  to  serve  as 
a  parachute — its  contact  with  the  ground  conies  too 
quickly. 

Lesson  in  Recent  Accidents. 

Among  the  more  recent  fatalities  in  aviation  are  the 
deaths  of  Antonio  Fernandez  and  Leon  Delagrange.  True 
former  was  thrown  to  the  ground  by  a  sudden  stoppage 
of  his  motor,  the  entire  machine  seeming  to  collapse. 
It  is  evident  there  were  radical  defects,  not  only  in  the 
motor,  but  in  the  aeroplane  framework  as  well.  At  the 
time  of  the  stoppage  it  is  estimated  that  Fernandez  was 
up  about  1,500  feet,  but  the  machine  got  no  opportunity 
to  exert  a  parachute  effect,  as  it  broke  up  immediately. 
This  would  indicate  a  fatal  weakness  in  the  structure 
which,  under  proper  testing,  could  probably  have  been 
detected  before  it  was  used  in  flight. 

It  is  hard  to  say  it,  but  Delagrange  appears  to  have 
been  culpable  to  great  degree  in  overloading  his  ma- 
chine with  a  motor  equipment  much  heavier  than  it  was 
designed  to  sustain.  He  was  65  feet  up  in  the  air  when 
the  collapse  occurred,  resulting  in  his  death.  As  in  the 
case  of  Fernandez  common-sense  precaution  would 
doubtless  have  prevented  the  fatality. 

Aviation  Not  Extra  Hazardous. 

All  told  there  have  been,  up  to  the  time  of  this  writing 
(April,  1910),  just  five  fatalities  in  the  history  of  power- 
driven  aviation.  This  is  surprisingly  low  when  the  na- 
ture of  the  experiments,  and  the  fact  that  most  of  the 


CONSTRUCTION   AND    OPERATION  143 

operators  were  far  from  having  extended  experience,  is 
taken  into  consideration.  Men  like  the  Wrights,  Curtiss, 
Bleriot,  Farman,  Paulhan  and  others,  are  now  experts, 
but  there  was  a  time,  and  it  was  not  long  ago,  when  they 
were  unskilled.  That  they,  with  numerous  others  less 
widely  known,  should  have  come  safely  through  their 
many  experiments  would  seem  to  disprove  the  prevailing 
idea  that  aviation  is  an  extra  hazardous  pursuit. 

In  the  hands  of  careful,  quick-witted,  nervy  men  the 
sailing  of  an  airship  should  be  no  more  hazardous  than 
the  sailing  of  a  yacht.  A  vessel  captain  with  common 
sense  will  not  go  to  sea  in  a  storm,  or  navigate  a  weak, 
unseaworthy  craft.  Neither  should  an  aviator  attempt 
to  sail  when  the  wind  is  high  and  gusty,  nor  with  a  ma- 
chine which  has  not  been  thoroughly  tested  and  found  to 
be  strong  and  safe. 

Safer  Than  Railroading. 

Statistics  show  that  some  12,000  people  are  killed  and 
72,000  injured  every  year  on  the  railroads  of  the  United 
States.  Come  to  think  it  over  it  is  small  wonder  that 
the  list  of  fatalities  is  so  large.  Trains  are  run  at  high 
speeds,  dashing  over  crossings  at  which  collisions  are 
liable  to  occur,  and  over  bridges  which  often  collapse 
or  are  swept  away  by  floods.  Still,  while  the  number  of 
casualties  is  large,  the  actual  percentage  is  small  con- 
sidering the  immense  number  of  people  involved. 

It  is  so  in  aviation.  The  number  of  casualties  is  re- 
markably small  in  comparison  with  the  number  of  flights 
made.  In  the  hands  of  competent  men  the  sailing  of  an 
airship  should  be,  and  is,  freer  from  risk  of  accident  than 
the  running  of  a  railway  train.  There  are  no  rails  to 
spread  or  break,  no  bridges  to  collapse,  no  crossings  at 
which  collisions  may  occur,  no  chance  for  some  sleepy 
or  overworked  employee  to  misunderstand  the  dis- 
patcher's orders  and  cause  a  wreck. 


144  FLYING   MACHINES: 

Two  Main  Causes  of  Trouble. 

The  two  main  causes  of  trouble  in  an  airship  leading 
to  disaster  may  be  attributed  to  the  stoppage  of  the 
motor,  and  the  aviator  becoming  rattled  so  that  he  loses 
control  of  his  machine.  Modern  ingenuity  is  fast  devel- 
oping motors  that  almost  daily  become  more  and  more 
reliable,  and  experience  is  making  aviators  more  and 
more  self-confident  in  their  ability  to  act  wisely  and 
promptly  in  cases  of  emergency.  Besides  this  a  satis- 
factory system  of  automatic  control  is  in  a  fair  way 
of  being  perfected. 

Occasionally  even  the  most  experienced  and  competent 
of  men  in  all  callings  become  careless  and  by  foolish 
action  invite  disaster.  This  is  true  of  aviators  the  same 
as  it  is  of  railroaders,  men  who  work  in  dynamite  mills, 
etc.  But  in  nearly  every  instance  the  responsibility  rests 
with  the  individual ;  not  with  the  system.  There  are 
some  men  unfitted  by  nature  for  aviation,  just  as  there 
are  others  unfitted  to  be  railway  engineers. 


CHAPTER   XVI. 

RADICAL  CHANGES  BEING  MADE. 

Changes,  many  of  them  extremely  radical  in  their  na- 
ture, are  continually  being  made  by  prominent  aviators, 
and  particularly  those  who  have  won  the  greatest  amount 
of  success.  Wonderful  as  the  results  have  been  few  of 


Sectional  View   of   New   Wright   Machine. 

the  aviators  are  really  satisfied.  Their  successes  have 
merely  spurred  them  on  to  new  endeavors,  the  ultimate 
end  being  the  development  of  an  absolutely  perfect  air- 
craft. 

Among  the   men   who  have  been   thus   experimenting 
are  the  Wright  Brothers,  who  last  year   (1909)  brought 

145 


146  FLYING   MACHINES: 

out  a  craft  totally  different  as  regards  proportions  and 
weight  from  the  one  used  the  preceding  year.  One 
marked  result  was  a  gain  of  about  3^  miles  an  hour  in 
speed. 

Dimensions  of  1908  Machine. 

The  1908  model  aeroplane  was  40  by  29  feet  over  all. 
The  carrying  surfaces,  that  is,  the  two  aerocurves,  were 
40  by  6  feet,  having  a  parabolical  curve  of  one  in  twelve. 
With  about  70  square  feet  of  surface  in  the  rudders,  the 
total  surface  given  was  about  550  square  feet.  The 
engine,  which  is  the  invention  of  the  Wright  brothers, 
weighed,  approximately,  200  pounds,  and  gave  about  25 
horsepower  at  1,400  revolutions  per  minute.  The  total 
weight  of  the  aeroplane,  exclusive  of  passenger,  but  in- 
clusive of  engine,  was  about  1,150  pounds.  This  result 
showed  a  lift  of  a  fraction  over  2j4  pounds  to  the  square 
foot  of  carrying  surface.  The  speed  desired  was  40 
miles  an  hour,  but  the  machine  was  found  to  make  only 
a  scant  39  miles  an  hour.  The  upright  struts  were 
about  %-inch  thick,  the  skids,  2,y2  by  i]/\  inches  thick. 

Dimensions  of   1909  Machine. 

The  1909  aeroplane  was  built  primarily  for  greater 
speed,  and  relatively  heavier ;  to  be  less  at  the  mercy 
of  the  wind.  This  result  was  obtained  as  follows:  The 
aerocurves,  or  carrying  surfaces,  were  reduced  in  dimen- 
sions from  40  by  6  feet  to  36  by  5^2  feet,  the  curve  re- 
maining the  same,  one  in  twelve.  The  upright  struts 
were  cut  from  seven-eighths  inch  to  five-eighths  inch,  and 
the  skids  from  two  and  one-half  by  one  and  one-quarter 
to  two  and  one-quarter  by  one  and  three-eighths  inches. 
This  result  shows  that  there  were  some  81  square  feet 
of  carrying  surface  missing  over  that  of  last  year's 
model.,  and  some  25  pounds  loss  of  weight.  Relatively, 


CONSTRUCTION   AND   OPERATION 


147 


though,  the  1909  model  aeroplane,  while  actually  25 
pounds  lighter,  is  really  some  150  pounds  heavier  in  the 
air  than  the  1908  model,  owing  to  the  lesser  square 
feet  of  carrying  surface. 

Some  of  the  Results  Obtained. 

Reducing   the    carrying   surfaces   from   6   to    5^2    feet 


Outline  of  Santos-Dumont's  Monoplane  as  Seen  From  Above. 

gave  two  results — first,  less  carrying  capacity ;  and,  sec- 
ond, less  head-on  resistance,  owing  to  the  fact  that  the 
extent  of  the  parabolic  curve  in  the  carrying  surfaces 
was  shortened.  The  "head-on"  resistance  is  the  retard- 
ance  the  aeroplane  meets  in  passing  through  the  air, 
and  is  counted  in  square  feet.  In  the  1908  model  the 
curve  being  one  in  twelve  and  6  feet  deep,  gave  6  inches 
of  head-on  resistance.  The  plane  being  40  feet  spread, 


148  FLYING   MACHINES: 

gave  6  inches  by  40  feet,  or  20  square  feet  of  head-on 
resistance.  Increasing  this  figure  by  a  like  amount  for 
each  plane,  and  adding  approximately  10  square  feet  for 
struts,  skids  and  wiring,  we  have  a  total  of  approximate- 
ly, 50  square  feet  of  surface  for  "head-on"  resistance. 

In  the  1909  aeroplane,  shortening  the  curve  6  inches 
at  the  parabolic  end  of  the  curve  took  off  i  inch  of 
head-on  resistance.  Shortening  the  spread  of  the  planes 
took  off  between  3  and  4  square  feet  of  head-on  resist- 
ance. Add  to  this  the  total  of  7  square  feet,  less  curve 
surface  and  about  I  square  foot,  less  wire  and  wood- 
work resistance,  and  we  have  a  grand  total  of,  approxi- 
mately, 12  square  feet  of  less  "head-on"  resistance  over 
the  1908  model. 

Changes  in  Engine  Action. 

The  engine  used  in  1909  was  the  same  one  used  in 
1908,  though  some  minor  changes  were  made  as  im- 
provements ;  for  instance,  a  make  and  break  spark  was 
used,  and  a  nine-tooth,  instead  of  a  ten-tooth  magneto 
gear-wheel  was  used.  This  increased  the  engine  revolu- 
tions per  minute  from  1,200  to  1,400,  and  the  propeller 
revolutions  per  minute  from  350  to  371,  giving  a  pro- 
peller thrust  of,  approximately,  170  foot  pounds  instead 
of  153,  as  was  had  last  year. 

More   Speed  and  Same  Capacity. 

One  unsatisfactory  feature  of  the  1909  model  over 
that  of  1908,  apparently,  was  the  lack  of  inherent  lateral 
stability.  This  was  caused  by  the  lesser  surface  and 
lesser  extent  of  curvatures  at  the  portions  of  the  aero- 
plane which  were  warped.  This  defect  did  not  show  so 
plainly  after  Mr.  Orville  Wright  had  become  fully  pro- 
ficient in  the  handling  of  the  new  machine,  and  with 
skillful  management,  the  1909  model  aeroplane  will  be 


CONSTRUCTION  AND    OPERATION 


149 


just  as  safe  and  secure  as  the  other  though  it  will  take 
a  little  more  practice  to  get  that  same  degree  of  skill. 

To  sum   up :     The   aeroplane   used   in    1909    was    25 
pounds  lighter,  but  really  about  150  pounds  heavier  in 


Side  View  of  Santos-Dumont's   Monoplane. 

the  air,  had  less  head-on  resistance,  and  greater  pro- 
peller thrust.  The  speed  was  increased  from  about  39 
miles  per  hour  to  42^  miles  per  hour.  The  lifting  ca- 
pacity remained  about  the  same,  about  450  pounds  ca- 
pacity passenger-weight,  with  the  1908  machine.  In  this 


Front  View  of  Santos-tDumont  Monoplane. 

respect,  the  loss  of  carrying  surface  was  compensated  for 
by  the  increased  speed. 

During  the  first  few  flights  it  was  plainly  demon- 
strated that  it  would  need  the  highest  skill  to  properly 
handle  the  aeroplane,  as  first  one  end  and  then  the  other 
would  dip  and  strike  the  ground,  and  either  tear  the  can- 
vas or  slew  the  aeroplane  around  and  break  a  skid. 


150  FLYING   MACHINES: 

Wrights  Adopt  Wheeled  Gears. 

In  still  another  important  respect  the  Wrights,  so  far 
as  the  output  of  one  of  their  companies  goes,  have  made 
a  radical  change.  All  the  aeroplanes  turned  out  by  the 
Deutsch  Wright  Gesellschaft,  according  to  the  German 
publication,  Automobil-Welt,  will  hereafter  be  equipped 
with  wheeled  running  gears  and  tails.  The  plan  of  this 
new  machine  is  shown  in  the  illustration  on  page  145. 
The  wheels  are  three  in  number,  and  are  attached  one 
to  each  of  the  two  skids,  just  under  the  front  edge  of 
the  planes,  and  one  forward  of  these,  attached  to  a  cross- 
member.  It  is  asserted  that  with  these  wheels  the 
teaching  of  purchasers  to  operate  the  machines  is  much 
simplified,  as  the  beginners  can  make  short  flights  on 
their  own  account  without  using  the  starting  derrick. 

This  is  a  big  concession  for  the  Wrights  to  make,  as 
they  have  hitherto  adhered  stoutly  to  the  skid  gear. 
While  it  is  true  they  do  not  control  the  German  com- 
pany producing  their  aeroplanes,  yet  the  nature  of  their 
connection  with  the  enterprise  is  such  that  it  may  be 
taken  for  granted  no  radical  changes  in  construction 
would  be  made  without  their  approval  and  consent. 

Only  Three  Dangerous  Rivals. 

Official  trials  with  the  1909  model  smashed  many  rec- 
ords and  leave  the  Wright  brothers  with  only  three  dan- 
gerous rivals  in  the  field,  and  with  basic  patents  which 
cover  the  curve,  warp  and  wing-tip  devices  found  on 
all  the  other  makes  of  aeroplanes.  These  three  rivals 
are  the  Curtiss  and  Voisin  biplane  type  and  the  Bleriot 
monoplane  pattern. 

The  Bleriot  monoplane  is  probably  the  most  danger- 
ous rival,  as  this  make  of  machine  has  a  record  of  54 
miles  per  hour,  has  crossed  the  English  channel  ^nd 
has  lifted  two  passengers  besides  the  operator.  The  lat- 


CONSTRUCTION   AND    OPERATION 


151 


152  FLYING   MACHINES: 

est  type  of  this  machine  only  weighs  771.61  pounds  com- 
plete, without  passengers,  and  will  lift  a  total  passenger 
weight  of  462.97  pounds,  which  is  a  lift  of  5.21  pounds 
to  the  square  foot.  This  is  a  bettei  result  than  those 
published  by  the  Wright  brothers,  the  best  noted  being 
4.25  pounds  per  square  foot. 

Other  Aviators  at  Work. 

The  Wrights,  however,  are  not  alone  in  their  efforts 
to  promote  the  efficiency  of  the  flying  machine.  Other 
competent  inventive  aviators,  notably  Curtiss,  Voisin, 
Bleriot  and  Farman,  are  close  after  them.  The  Wrights, 
as  stated,  have  a  marked  advantage  in  the  possession  of 
patents  covering  surface  plane  devices  which  have  thus 
far  been  found  indispensable  in  flying  machine  construc- 
tion. Numerous  law  suits  growing  out  of  alleged  in- 
fringements of  these  patents  have  been  started,  and 
others  are  threatened.  What  effect  these  actions  will 
have  in  deterring  aviators  in  general  from  proceeding 
with  their  experiments  remains  to  be  seen. 

In  the  meantime  the  four  men  named — Curtiss,  Voisin, 
Bleriot  and  Farman — are  going  ahead  regardless  of  con- 
sequences, and  the  inventive  genius  of  each  is  so  strong 
that  it  is  reasonable  to  expect  some  remarkable  develop- 
ments in  the  near  future. 

Smallest  of  Flying  Machines. 

To  Santos  Dumont  must  be  given  the  credit  of  pro- 
ducing the  smallest  practical  flying  machine  yet  con- 
structed. True,  he  has  done  nothing  remarkable  with  it 
in  the  line  of  speed,  but  he  has  demonstrated  the  fact 
that  a  large  supporting  surface  is  not  an  essential  feature. 

This  machine  is  named  "La  Demoiselle."  It  is  a  mono- 
plane of  the  dihedral  type,  with  a  main  plane  on  each 


CONSTRUCTION  AND    OPERATION  153 

side  of  the  center.  These  main  planes  are  of  18  foot 
spread,  and  nearly  6^2  feet  in  depth,  giving  approximately 
115  feet  of  surface  area.  The  total  weight  is  242  pounds, 
which  is  358  pounds  less  than  any  other  machine  which 
has  been  successfully  used.  The  total  depth  from  front 
to  rear  is  26  feet. 


Position  of  Motor  on  Brauner-Smith  Machine. 

The  framework  is  of  bamboo,  strengthened  and  held 
taut  with  wire  guys. 

Have  One  Rule  in  Mind. 

In  this  struggle  for  mastery  in  flying  machine  effici- 
ency all  the  contestants  keep  one  rule  in  mind,  and  this 
is: 

"The  carrying  capacity  of  an  aeroplane  is  governed 
by  the  peripheral  curve  of  its  carrying  surfaces,  plus  the 
speed;  and  the  speed  is  governed  by  the  thrust  of  the 
propellers,  less  the  'head-on'  resistance." 


154  FLYING   MACHINES: 

Their  ideas  as  to  the  proper  means  of  approaching 
the  proposition  may,  and  undoubtedly  are,  at  variance, 
but  the  one  rule  in  solving  the  problem  of  obtaining  the 
greatest  carrying  capacity  combined  with  the  greatest 
speed,  obtains  in  all  instances. 


CHAPTER  XVII. 

SOME  OF  THE  NEW  DESIGNS. 

Spurred  on  by  the  success  attained  by  the  more  expe- 
rienced and  better  known  aviators  numerous  inventors 
of  lesser  fame  are  almost  daily  producing  practical  fly- 
ing machines  varying  radically  in  construction  from 
those  now  in  general  use. 

One  of  these  comparatively  new  designs  is  the  Van 


How  the  New  Van  Anden  Machine  Looks. 

Anden  biplane,  made  by  Frank  Van  Anden  of  Islip, 
Long  Island,  a  member  of  the  New  York  Aeronautic 
Society.  While  his  machine  is  wholly  experimental, 
many  successful  short  flights  were  made  with  it  last  fall 
(1909).  One  flight,  made  October  iQth,  1909,  is  of  par- 

155 


156  FLYING   MACHINES: 

ticular  interest  as  showing  the  practicability  of  an  auto- 
matic stabilizing  device  installed  by  the  inventor.  The 
machine  was  caught  in  a  sudden  severe  gust  of  wind 
and  keeled  over,  but  almost  immediately  righted  itself, 
thus  demonstrating  in  a  most  satisfactory  manner  the 
value  of  one  new  attachment. 

Features  of  Van  Anden  Model. 

In  size  the  surfaces  of  the  main  biplane  are  26  feet 
in  spread,  and  4  feet  in  depth  from  front  to  rear.  The 
upper  and  lower  planes  are  4  feet  apart.  Silkolene 
coated  with  varnish  is  used  for  the  coverings.  Ribs 
(spruce)  are  curved  one  inch  to  the  foot,  the  deepest 
part  of  the  curve  (4  inches)  being  one  foot  back  from  the 
front  edge  of  the  horizontal  beam.  Struts  (also  of 
spruce,  as  is  all  the  framework)  are  elliptical  in  shape. 
The  main  beams  are  in  three  sections,  nearly  half  round 
in  form,  and  joined  by  metal  sleeves. 

There  is  a  tw^o-surface  horizontal  rudder,  2x2x4  feet> 
in  front.  This  is  pivoted  at  its  lateral  center  8  feet  from 
the  front  edge  of  the  main  planes.  In  the  rear  is  an- 
other two-surface  horizontal  rudder  2x2x2^  feet,  pivoted 
in  the  same  manner  as  the  front  one,  15  feet  from  the 
rear  edges  of  the  main  planes. 

Hinged  to  the  rear  central  strut  of  the  rear  rudder 
is  a  vertical  rudder  2  feet  high  by  3  feet  in  length. 

The   Method  of  Control. 

In  the  operation  of  these  rudders — both  front  and  rear 
— and  the  elevation  and  depression  of  the  main  planes, 
the  Curtiss  system  is  employed.  Pushing  the  steering- 
wheel  post  outward  depresses  the  front  edges  of  the 
planes,  and  brings  the  machine  downward ;  pulling  the 
steering-wheel  post  inward  elevates  the  front  edges  of 
the  planes  and  causes  the  machine  to  ascend. 


CONSTRUCTION  AND    OPERATION 


157 


Turning  the  steering  wheel  itself  to  the  right  swings 
the  tail  rudder  to  the  left,  and  the  machine,  obeying  this 
like  a  boat,  turns  in  the  same  direction  as  the  wheel 
is  turned.  By  like  cause  turning  the  wheel  to  the  left 
turns  the  machine  to  the  left. 


Walden's  Automatic  Stability  System. 

The  four  tubes  represent  the  4-cylinder  motor;  A — engine 
shaft;  B — auxiliary  shaft;  D,  D,  D — ball  bearings;  E,  E — separat- 
ing rods;  F  and  G — methods  of  attaching  propeller. 

Automatic  Control  of  Wings. 

There  are  two  wing  tips,  each  of  6  feet  spread  (length) 
and  2  feet  from  front  to  rear.  These  are  hinged  half 
way  between  the  main  surfaces  to  the  two  outermost 
rear  struts.  Cables  run  from  these  to  an  automatic 
device  working  with  power  from  the  engine,  which  an- 


158  FLYING   MACHINES: 

tomatically  operates  the  tips  with  the  tilting  of  the 
machine.  Normally  the  wing  tips  are  held  horizontal 
by  stiff  springs  introduced  in  the  cables  outside  of  the 
device. 

It  was  the  successful  working  of  this  device  which 
righted  the  Van  Anden  craft  when  it  was  overturned  in 
the  squall  of  October  iQth,  1909.  Previous  to  that 
occurrence  Mr.  Van  Anden  had  looked  upon  the  device 
as  purely  experimental,  and  had  admitted  that  he  had 
grave  uncertainty  as  to  how  it  would  operate  in  time  of 
emergency.  He  is  now  quoted  as  being  thoroughly  sat- 
isfied with  its  practicability.  It  is  this  automatic  device 
which  gives  the  Van  Anden  machine  at  least  one  dis- 
tinctively new  feature. 

While  on  this  subject  it  will  not  be  amiss  to  add  that 
Mr.  Curtiss  does  not  look  kindly  on  automatic  control. 
"I  would  rather  trust  to  my  own  action  than  that  of  n 
machine,"  he  says.  This  is  undoubtedly  good  logic  so 
far  as  Mr.  Curtiss  is  concerned,  but  all  aviators  are  not 
so  cool-headed  and  resourceful. 

Motive  Power  of  Van  Anden. 

A  5ohorsepower  "H-F"  water  cooled  motor  drives  a 
laminated  wood  propeller  6  feet  in  diameter,  with  a  17 
degree  pitch  at  the  extremities,  increasing  toward  the 
hub.  The  rear  end  of  the  motor  is  about  6  inches  back 
from  the  rear  transverse  beam  and  the  engine  shaft  is 
in  a  direct  line  with  the  axes  of  the  two  horizontal  rud- 
ders. An  R.  I.  V.  ball  bearing  carries  the  shaft  at  this 
point.  Flying,  the  motor  turns  at  about  800  revolutions 
per  minute,  delivering  180  pounds  pull.  A  test  of  the 
motor  running  at  1,200  showed  a  pull  of  250  pounds  on 
the  scales. 

Still  Another  New  Aeroplane. 

Another  new  aeroplane  is  that  produced  by    A.    M. 


CONSTRUCTION   AND    OPERATION 


159 


160  FLYING   MACHINES: 

Herring  (an  old-timer)  and  W.  S.  Burgess,  under  the 
name  of  the  Herring-Burgess.  This  is  also  equipped 
with  an  automatic  stability  device  for  maintaining  the 
balance  transversely.  The  curvature  of  the  planes  is 
also  laid  out  on  new  lines.  That  this  new  plan  is  ef- 
fective is  evidenced  by  the  fact  that  the  machine  has 
been  elevated  to  an  altitude  of  40  feet  by  using  one-half 
the  power  of  the  3O-horsepower  motor. 

The  system  of  rudder  and  elevation  control  is  very 
simple.  The  aviator  sits  in  front  of  the  lower  plane, 
and  extending  his  arms,  grasps  two  supports  which  ex- 
tend down  diagonally  in  front.  On  the  under  side  of 
these  supports  just  beneath  his  fingers  are  the  controls 
which  operate  the  vertical  rudder,  in  the  rear.  Thus,  if 
he  wishes  to  turn  to  the  right,  he  presses  the  control 
under  the  fingers  of  his  right  hand;  if  to  the  left,  that 
under  the  fingers  of  his  left  hand.  The  elevating  rud- 
der is  operated  by  the  aviator's  right  foot,  the  control 
being  placed  on  a  foot-rest. 

Motor  Is  Extremely  Light. 

Not  the  least  notable  feature  of  the  craft  is  its  motor. 
Although  developing,  under  load,  3o-horsepower,  or  that 
of  an  ordinary  automobile,  it  weighs,  complete,  hardly 
TOO  pounds.  Having  occasion  to  move  it  a  little  dis- 
tance for  inspection,  Mr.  Burgess  picked  it  up  and  walked 
off  with  it — cylinders,  pistons,  crankcase  and  all,  even 
the  magneto,  being  attached.  There  are  not  many  30- 
horsepower  engines  which  can  be  so  handled.  Every- 
thing about  it  is  reduced  to  its  lowest  terms  of  simplic- 
ity, and  hence,  of  weight.  A  single  camshaft  operates 
not  only  all  of  the  inlet  and  exhaust  valves,  but  the  mag- 
neto and  gear  water  pump,  as  well.  The  motor  is  placed 
directly  behind  the  operator,  and  the  propeller  is  direct- 
ly mounted  on  the  crankshaft. 


CONSTRUCTION   AND    OPERATION 


161 


This  weight  of  less  than  100  pounds,  it  must  be  re- 
membered, is  not  for  the  motor  alone ;  it  includes  the 
entire  power  plant  equipment. 

The  "thrust"  of  the  propeller  is  also  extraordinary, 
being  between  250  and  260  pounds.  The  force  of  the 
wind  displacement  is  strong  enough  to  knock  down  a 
good-sized  boy  as  one  youngster  ascertained  when  he 
got  behind  the  propeller  as  it  was  being  tested.  He 
was  not  only  knocked  down  but  driven  for  some  dis- 
tance away  from  the  machine.  The  propeller  has  four 
blades  which  are  but  little  wider  than  a  lath. 


Aeroplane  Constructed  by  U.  of  P.  Students. 

Machine  Built  by  Students. 

Students  at  the  University  of  Pennsylvania,  headed  by 
Laurence  J.  Lesh,  a  protege  of  Octave  Chanute,  have 
constructed  a  practical  aeroplane  of  ordinary  maximum 
size,  in  which  is  incorporated  many  new  ideas.  The 


162  FLYING   MACHINES: 

most  unique  of  these  is  to  be  found  in  the  steering  gear, 
and  the  provision  made  for  the  accommodation  of  a 
pupil  while  taking  lessons  under  an  experienced  aviator. 
Immediately  back  of  the  aviator  is  an  extra  seat  and 
an  extra  steering  wheel  which  works  in  tandem  style 
with  the  front  wheel.  By  this  arrangement  a  beginner 
may  be  easily  and  quickly  taught  to  have  perfect  con- 
trol of  the  machine.  These  tandem  wheels  are  also 
handy  for  passengers  who  may  wish  to  operate  the  car 
independently  of  one  another,  it  being  understood,  of 
course,  that  there  will  be  no  conflict  of  action. 

Frame  Size  and  Engine  Power. 

The  frame  has  36  feet  spread  and  measures  35  feet 
from  the  front  edge  to  the  end  of  the  tail  in  the  rear.  It 
is  equipped  with  two  rear  propellers  operated  by  a  Ram- 
sey 8-cylinder  motor  of  50  horsepower,  placed  horizon- 
tally across  the  lower  plane,  with  the  crank  shaft  run- 
ning clear  through  the  engine. 

The  "Pennsylvania  I"  is  the  first  two-propeller  biplane 
chainless  car,  this  scheme  having  been  adopted  in  order 
to  avoid  the  crossing  of  chains.  The  lateral  control  is 
by  a  new  invention  by  Octave  Chanute  and  Laurence  J. 
Lesh,  for  which  Lesh  is  now  applying  for  a  patent.  The 
device  was  worked  out  before  the  Wright  brothers'  suit 
was  begun,  and  is  said  to  be  superior  to  the  Wright 
warping  or  the  Curtiss  ailerons.  The  landing  device  is 
also  new  in  design.  This  aeroplane  will  weigh  about 
1,500  pounds,  and  will  carry  fuel  for  a  flight  of  150  miles, 
and  it  is  expected  to  attain  a  speed  of  at  least  45  miles 
an  hour. 

There  are  others,  lots  of  them,  too  numerous  in  fact 
to  admit  of  mention  in  a  book  of  this  size. 


CHAPTER  XVIII. 

DEMAND  FOR  FLYING  MACHINES. 

'  As  a  commercial  proposition  the  manufacture  and  sale 
of  motor-equipped  aeroplanes  is  making  much  more 
rapid  advance  than  at  first  obtained  in  the  similar 
handling  of  the  automobile.  Great,  and  even  phenom- 
enal, as  was  the  commercial  development  of  the  motor 
car,  that  of  the  flying  machine  is  even  greater.  This  is 
a  startling  statement,  but  it  is  fully  warranted  by  the 
facts. 

It  is  barely  more  than  a  year  ago  (1909)  that  atten- 
tion was  seriously  attracted  to  the  motor-equipped  aero- 
plane as  a  vehicle  possible  of  manipulation  by  others 
than  professional  aviators.  Up  to  that  time  such  actual 
flights  as  were  made  were  almost  exclusively  with  the 
sole  purpose  of  demonstrating  the  practicability  of  the 
machine,  and  the  merits  of  the  ideas  as  to  shape,  engine 
power,  etc.,  of  the  various  producers. 

Results   of   Bleriot's    Daring. 

It  was  not  until  Bleriot  flew  across  the  straits  of 
Dover  on  July  25th,  1909,  that  the  general  public  awoke 
to  a  full  realization  of  the  fact  that  it  was  possible  for 
others  than  professional  aviators  to  indulge  in  avia- 
tion. Bleriot's  feat  was  accepted  as  proof  that  at  last  an 
absolutely  new  means  of  sport,  pleasure  and  research, 
had  been  practically  developed,  and  was  within  the 

163 


164  FLYING   MACHINES: 

reach   of  all   who   had  the   inclination,  nerve  and  finan- 
cial means  to  adopt  it. 

From  this  event  may  be  dated  the  birth  of  the  mod- 
ern riving  machine  into  the  world  of  business.  The  auto- 
mobile was  taken  up  by  the  general  public  from  the 
very  start  because  it  was  a  proposition  comparatively 
easy  of  demonstration.  There  was  nothing  mysterious 
or  uncanny  in  the  fact  that  a  wheeled  vehicle  could  be 
propelled  on  solid,  substantial  roads  by  means  of  engine 
power.  And  yet  it  took  (comparatively  speaking)  a  long 
time  to  really  popularize  the  motor  car. 

Wonderful  Results  in  a  Year. 

Men  of  large  financial  means  engaged  in  the  manufac- 
ture of  automobiles,  and  expended  fortunes  in  attract- 
ing public  attention  to  them  through  the  medium  of 
advertisements,  speed  and  road  contests,  etc.  By  these 
means  a  mammoth  business  has  been  built  up,  but  bring- 
ing this  business  to  its  present  proportions  required 
years  of  patient  industry  and  indomitable  pluck. 

At  this  writing,  less  than  a  year  from  the  day  when 
Bleriot  crossed  the  channel,  the  actual  sales  of  flying 
machines  outnumber  the  actual  sales  of  automobiles  in 
the  first  year  of  their  commercial  development.  This, 
may  appear  incredible,  but  it  is  a  fact  as  statistics  will 
show. 

In  this  connection  we  should  take  into  consideration 
the  fact  that  up  to  a  year  ago  there  was  no  serious  in- 
tention of  putting  flying  machines  on  the  market ;  no 
preparations  had  been  made  to  produce  them  on  a  com- 
mercial scale ;  no  money  had  been  expended  in  adver- 
tisements with  a  view  to  selling  them. 

Some  of  the   Actual   Results. 

Today  flying  machines  are  being  produced  on  a  com- 
mercial basis,  and  there  is  a  big  demand  for  them.  The 


CONSTRUCTION  AND    OPERATION  165 

people  making  them  are  overcrowded  with  orders.  Some 
of  the  producers  are  already  making  arrangements  to 
enlarge  their  plants  and  advertise  their  product  for  sale 
the  same  as  is  being  done  with  automobiles,  while  a 
number  of  flying  machine  motor  makers  are  already 
promoting  the  sale  of  their  wares  in  this  way. 

Here  are  a  few  actual  figures  of  flying  machine  sales 
made  by  the  more  prominent  producers  since  July  25th, 
1909: 

Santos  Dumont,  90  machines :  Bleriot,  200 ;  Farman, 
130;  Clemenceau-Wright,  80;  Voisin,  100;  Antoinette, 
TOO.  Many  of  these  orders  have  been  filled  by  delivery 
of  the  machines,  and  in  others  the  construction  work 
is  under  way. 

The  foregoing  are  all  of  foreign  make.  In  this  coun- 
try Curtiss  and  the  Wrights  are  engaged  in  similar 
work,  but  no  actual  figures  of  their  output  are  obtain- 
able. 

Larger  Plants  Are  Necessary. 

And  this  situation  exists  despite  the  fact  that  none  of 
the  producers  are  really  equipped  with  adequate  plants 
for  turning  out  their  machines  on  a  modern,  business- 
like basis.  The  demand  was  so  sudden  and  unexpected 
that  it  found  them  poorly  prepared  to  meet  it.  This, 
however,  is  now  being  remedied  by  the  erection  of  spe- 
cial plants,  the  enlargement  of  others,  and  the  intro- 
duction of  new  machinery  and  other  labor-saving  con- 
veniences. 

Companies,  with  large  capitalization,  to  engage  in  the 
exclusive  production  of  airships  are  being  organized  in 
many  parts  of  the  world.  One  notable  instance  of  this 
nature  is  worth  quoting  as  illustrative  of  the  manner 
in  which  the  production  of  flying  machines  is  being  com- 
mercialized. This  is  the  formation  at  Frankfort,  Ger- 
many, of  the  Flugmaschine  Wright,  G.  m.  b.  H.,  with 


166  FLYING   MACHINES: 

a  capital  of  $119,000,  the  Krupps,  of  Essen,  being  inter- 
ested. 

Prices  at  Which  Machines  Sell. 

This  wonderful  demand  from  the  public  has  come  not- 
withstanding the  fact  that  the  machines,  owing  to  lack 
of  facilities  for  wholesale  production,  are  far  from  be- 
ing cheap.  Such  definite  quotations  as  are  made  are 
on  the  following  basis: 

Santos  Dumont — List  price  $1,000,  but  owing  to  the 
rush  of  orders  agents  are  readily  getting  from  $1,300  to 
$1,500.  This  is  the  smallest  machine  made. 

Bleriot — List  price  $2,500.  This  is  for  the  cross- 
channel  type,  with  Anzani  motor. 

Antoinette — List  price  from  $4,000  to  $5,000,  accord- 
ing to  size. 

Wright — List  price  $5,600. 

Curtiss — List  price  $5,000. 

There  is,  however,  no  stability  in  prices  as  purchasers 
are  almost  invariably  ready  to  pay  a  considerable  pre- 
mium to  facilitate  delivery. 

The  motor  is  the  most  expensive  part  of  the  flying 
machine.  Motor  prices  range  from  $500  to  $2,000,  this 
latter  amount  being  asked  for  the  Curtiss  engine. 

Systematic  Instruction  of  Amateurs. 

In  addition  to  the  production  of  flying  machines  many 
of  the  experienced  aviators  are  making  a  business  of 
the  instruction  of  amateurs.  Curtiss  and  the  Wrights 
in  this  country  have  a  number  of  pupils,  as  have  also 
the  prominent  foreigners.  Schools  of  instruction  are 
being  opened  in  various  parts  of  the  world,  not  alone  as 
private  money-making  ventures,  but  in  connection  with 
public  educational  institutions.  One  of  these  latter  is 
to  be  found  at  the  University  of  Barcelona,  Spain. 

The  flying  machine  agent,  the  man  who  handles  the 


CONSTRUCTION  AND   OPERATION 


167 


168  FLYING   MACHINES: 

machines  on  a  commission,  has  also  become  a  known 
quantity,  and  will  soon  be  as  numerous  as  his  brother 
of  the  automobile.  The  sign  "Jonn  Bird,  agent  for  Skim- 
mer's Flying  Machine,"  is  no  longer  a  curiosity. 

Yes,  the  Airship  Is  Here. 

From  all  of  which  we  may  well  infer  that  the  flying 
machine  in  practical  form  has  arrived,  and  that  it  is 
here  to  stay.  It  is  no  exaggeration  to  say  that  the  time 
is  close  at  hand  when  people  will  keep  flying  machines 
just  as  they  now  keep  automobiles,  and  that  pleasure 
jaunts  will  be  fully  as  numerous  and  popular.  With 
the  important  item  of  practicability  fully  demonstrated, 
"Come,  take  a  trip  in  my  airship,"  will  have  more  real 
significance  than  now  attaches  to  the  vapid  warblings 
of  the  vaudeville  vocalist. 

As  a  further  evidence  that  the  airship  is  really  here, 
and  that  its  presence  is  recognized  in  a  business  way, 
the  action  of  life  and  accident  insurance  companies  is 
interesting.  Some  of  them  are  reconstructing  their  poli- 
cies so  as  to  include  a  special  waiver  of  insurance  by 
aviators.  Anything  which  compels  these  great  corpora- 
tions to  modify  their  policies  cannot  be  looked  upon  as 
a  mere  curiosity  or  toy. 

It  is  some  consolation  to  know  that  the  movement  in 
this  direction  is  not  thus  far  widespread.  Moreover  it 
is  more  than  probable  that  the  competition  for  busi- 
ness will  eventually  induce  the  companies  to  act  more 
liberally  toward  aviators,  especially  as  the  art  of  avia- 
tion advances. 


CHAPTER  XIX. 

LAW  OF  THE  AIRSHIP. 

Successful  aviation  has  evoked  some  peculiar  things 
in  the  way  of  legal  action  and  interpretation  of  the  law. 

It  is  well  understood  that  a  man's  property  cannot 
be  used  without  his  consent.  This  is  an  old  established 
principle  in  common  law  which  holds  good  today. 

The  limits  of  a  man's  property  lines,  however,  have 
not  been  so  well  understood  by  laymen.  According  to 
eminent  legal  authorities  such  as  Blackstone,  Littleton 
and  Coke,  the  "fathers  of  the  law,"  the  owner  of  realty 
also  holds  title  above  and  below  the  surface,  and  this 
theory  is  generally  accepted  without  question  by  the 
courts. 

Rights  of  Property  Owners. 

In  other  words  the  owner  of  realty  also  owns  the  sky 
above  it  without  limit  as  to  distance.  He  can  dig  as 
deep  into  his  land,  or  go  as  high  into  the  air  as  he  de- 
sires, provided  he  does  not  trespass  upon  or  injure  similar 
rights  of  others. 

The  owner  of  realty  may  resist  by  force,  all  other 
means  having  failed,  any  trespass  upon,  or  invasion  of 
his  property.  Other  people,  for  instance,  may  not  enter 
upon  it,  or  over  or  under  it,  without  his  express  per- 
mission and  consent.  There  is  only  one  exception,  and 
this  is  in  the  case  of  public  utility  corporations  such  as 
railways  which,  under  the  law  of  eminent  domain,  may 
condemn  a  right  of  way  across  the  property  of  an  ob- 

169 


170  FLYING   MACHINES: 

stinate  owner  who  declines  to  accept  a  fair  price  for  the 
privilege. 

Privilege  Sharply  Confined. 

The  law  of  eminent  domain  may  be  taken  advantage 
of  only  by  corporations  which  are  engaged  in  serving 
the  public.  It  is  based  upon  the  principle  that  the  ad- 
vancement and  improvement  of  a  community  is  of  more 
importance  and  carries  with  it  more  rights  than  the  in- 
terests of  the  individual  owner.  But  even  in  cases  where 
the  right  of  eminent  domain  is  exercised  there  can  be  no 
confiscation  of  the  individual's  property. 

Exercising  the  right  of  eminent  domain  is  merely  ob- 
taining by  public  purchase  what  is  held  to  be  essential 
to  the  public  good,  and  which  cannot  be  secured  by  pri- 
vate purchase.  When  eminent  domain  proceedings  are 
resorted  to  the  court  appoints  appraisers  who  determine 
upon  the  value  of  the  property  wanted,  and  this  value 
(in  money)  is  paid  to  the  owner. 

How  It  Affects  Aviation. 

It  should  be  kept  in  mind  that  this  privilege  of  the 
"right  of  eminent  domain"  is  accorded  only  to  corpora- 
tions which  are  engaged  in  serving  the  public.  Individ- 
uals cannot  take  advantage  of  it.  Thus  far  all  aviation 
has  been  conducted  by  individuals ;  there  are  no  flying 
machine  or  airship  corporations  regularly  engaged  in  the 
transportation  of  passengers,  mails  or  freight. 

This  leads  up  to  the  question  "What  would  happen  if 
realty  owners  generally,  or  in  any  considerable  numbers, 
should  prohibit  the  navigation  of  the  air  above  their 
holdings?"  It  is  idle  to  say  such  a  possibility  is  ridicu- 
lous— it  is  already  an  actuality  in  a  few  individual  in- 
stances. 

One  property  owner  in  New  Jersey,  a  justice  of  the 
peace,  maintains  a  large  sign  on  the  roof  of  his  house 


CONSTRUCTION  AND   OPERATION  171 

warning  aviators  that  they  must  not  trespass  upon  his 
domain.  That  he  is  acting  well  within  his  rights  in  do- 
ing this  is  conceded  by  legal  authorities. 

Hard  to  Catch  Offenders. 

But,  suppose  the  alleged  trespass  is  committed,  what 
is  the  property  owner  going  to  do  about  it?  He  must 
first  catch  the  trespasser  and  this  would  be  a  pretty  hard 
job.  He  certainly  could  not  overtake  him,  unless  he 
kept  a  racing  aeroplane  for  this  special  purpose.  It 
would  be  equally  difficult  to  indentify  the  offender  after 
the  offense  had  been  committed,  even  if  he  were  located, 
as  aeroplanes  carry  no  license  numbers. 

Allowing  that  the  offender  should  be  caught  the  only 
recourse  of  the  realty  owner  is  an  action  for  damages. 
He  may  prevent  the  commission  of  the  offense  by  force 
if  necessary,  but  after  it  is  committed  he  can  only  sue 
for  damages.  And  in  doing  this  he  would  have  a  lot  of 
trouble. 

Points  to  Be  Proven. 

One  of  the  first  things  the  plaintiff  would  be  called 
upon  to  prove  would  be  the  elevation  of  the  machine. 
If  it  were  reasonably  close  to  the  ground  there  would, 
of  course,  be  grave  risk  of  damage  to  fences,  shrubbery, 
and  other  property,  and  the  court  would  be  justified  in 
holding  it  to  be  a  nuisance  that  should  be  suppressed. 

If,  on  the  other  hand,  the  machine  was  well  up  in  the 
air,  but  going  slowly,  or  hovering  over  the  plaintiff's 
property,  the  court  might  be  inclined  to  rule  that  it 
could  not  possibly  be  a  nuisance,  but  right  here  the  court 
would  be  in  serious  embarrassment.  By  deciding  that 
it  was  not  a  nuisance  he  would  virtually  override  the 
law  against  invasion  of  a  man's  property  without  his 
consent  regardless  of  the  nature  of  the  invasion.  By 
the  same  decision  he  would  also  say  in  effect  that,  if  one 


172  FLYING  MACHINES: 

flying  machine  could  do  this  a  dozen  or  more  would 
have  equal  right  to  do  the  same  thing.  While  one  ma- 
chine hovering  over  a  certain  piece  of  property  may  be 
no  actual  nuisance  a  dozen  or  more  in  the  same  position 
could  hardly  be  excused. 

Difficult  to  Fix  Damages. 

Such  a  condition  would  tend  to  greatly  increase  the 
risk  of  accident,  either  through  collision,  or  by  the  care- 
lessness of  the  aviators  in  dropping  articles  which  might 
cause  damages  to  the  people  or  property  below.  In 
such  a  case  it  would  undoubtedly  be  a  nuisance,  and 
in  addition  to  a  fine,  the  offender  would  also  be  liable 
for  the  damages. 

Taking  it  for  granted  that  no  actual  damage  is  done, 
and  the  owner  merely  sues  on  account  of  the  invasion 
of  his  property,  how  is  the  amount  of  compensation  to 
be  fixed  upon?  The  owner  has  lost  nothing;  no  part  of 
his  possessions  has  been  taken  away ;  nothing  has  been 
injured  or  destroyed ;  everything  is  left  in  exactly  the 
same  condition  as  before  the  invasion.  And  yet,  if  the 
law  is  strictly  interpreted,  the  offender  is  liable. 

Right  of  Way  for  Airships. 

Somebody  has  suggested  the  organization  of  flying- 
machine  corporations  as  common  carriers,  which  would 
give  them  the  right  of  eminent  domain  with  power  to 
condemn  a  right  of  way.  But  what  would  they  con- 
demn? There  is  nothing  tangible  in  the  air.  Railways 
in  condemning  a  right  of  way  specify  tangible  property 
(realty)  within  certain  limits.  How  would  an  aviator 
designate  any  particular  right  of  way  through  the  air 
a  certain  number  of  feet  in  width,  and  a  certain  distance 
from  the  ground? 

And  yet,  should  the  higher  courts  hold  to  the  letter 


CONSTRUCTION   AND   OPERATION  173 

of  the  law  and  decide  that  aviators  have  no  right  to 
navigate  their  craft  over  private  property,  something 
will  have  to  be  done  to  get  them  out  of  the  dilemma,  as 
aviation  is  too  far  advanced  to  be  discarded.  Fortu- 
nately there  is  little  prospect  of  any  widespread  antag- 
onism among  property  owners  so  long  as  aviators  re- 
frain from  making  nuisances  of  themselves. 

Possible  Solution  Offered. 

One  possible,  solution  is  offered  and  that  is  to  confine 
the  path  of  airships  to  the  public  highways  so  that  no- 
body's property  rights  would  be  invaded.  In  addition, 
as  a  matter  of  promoting  safety  for  both  operators  and 
those  who  may  happen  to  be  beneath  the  airships  as 
they  pass  over  a  course,  adoption  of  the  French  rules 
are  suggested.  These  are  as  follows : 

Aeroplanes,  when  passing,  must  keep  to  the  right,  and 
pass  at  a  distance  of  at  least  150  feet.  They  are  free 
from  this  rule  when  flying  at  altitudes  of  more  than  100 
feet.  Every  machine  when  flying  at  night  or  during 
foggy  weather  must  carry  a  green  light  on  the  right, 
and  a  red  light  on  the  left,  and  a  white  headlight  on  the 
front. 

These  are  sensible  rules,  but  may  be  improved  upon 
by  the  addition  of  a  signal  system  of  some  kind,  either 
horn,  whistle  or  bell. 

Responsibility  of  Aviators. 

Mr.  Jay  Carver  Bossard,  in  recent  numbers  of  Fly, 
brings  out  some  curious  and  interesting  legal  points  in 
connection  with  aviation,  among  which  are  the  follow- 
ing: 

"Private  parties  who  possess  aerial  craft,  and  desire 
to  operate  the  same  in  aerial  territory  other  than  their 
own,  must  obtain  from  land  owners  special  permission 


174  FLYING   MACHINES: 

to  do  so,  such  permission  to  be  granted  only  by  agree- 
ment, founded  upon  a  valid  consideration.  Otherwise, 
passing  over  another's  land  will  in  each  instance  amount 
to  a  trespass. 

"Leaving  this  highly  technical  side  of  the  question, 
let  us  turn  to  another  view:  the  criminal  and  tort  liabil- 
ity of  owners  and  operators  to  airship  passengers.  If 
A  invites  B  to  make  an  ascension  with  him  in  his  ma- 
chine, and  B,  knowing  that  A  is  merely  an  enthusiastic 
amateur  and  far  from  being  an  expert,  accepts  and  is 
through  A's  innocent  negligence  injured,  he  has  no 
grounds  for  recovery.  But  if  A  contracts  with  B,  to 
transport  him  from  one  place  to  another,  for  a  consid- 
eration, and  B  is  injured  by  the  poor  piloting  of  A, 
A  would  be  liable  to  B  for  damages  which  would  result. 
Now  in  order  to  safeguard  such  people  as  B,  curious  to 
the  point  of  recklessness,  the  law  will  have  to  require 
all  airship  operators  to  have  a  license,  and  to  secure 
this  license  airship  pilots  will  have  to  meet  certain  re- 
quirements. Here  again  is  a  question.  Who  is  going 
to  say  whether  an  applicant  is  competent  to  pilot  a  bal- 
loon or  airship? 

Fine  for  an   Aeronaut. 

"An  aeroplane  while  maneuvering  is  suddenly  caught 
by  a  treacherous  gale  and  swept  to  the  ground.  A  crowd 
of  people  hasten  over  to  see  if  the  aeronaut  is  injured, 
and  in  doing  so  trample  over  Tax-payer  Smith's  garden, 
much  to  the  detriment  of  his  -  growing  vegetables  and 
flowers.  Who  is  liable  for  the  damages?  Queer  as  it 
may  seem,  a  case  very  similar  to  this  was  decided  in 
1823,  in  the  New  York  supreme  court,  and  it  was  held 
that  the  aeronaut  was  liable  upon  the  following  grounds: 
'To  render  one  man  liable  in  trespass  for  the  acts  of 
others,  it  must  appear  either  that  they  acted  in  concert, 


CONSTRUCTION   AND    OPERATION  175 

or  that  the  act  of  the  one,  ordinarily  and  naturally  pro- 
duced the  acts  of  the  others.  Ascending  in  a  balloon  is 
not  an  unlawful  act,  but  it  is  certain  that  the  aeronaut 
has  no  control  over  its  motion  horizontally,  but  is  at 
the  sport  of  the  wind,  and  is  to  descend  when  and  how 
he  can.  His  reaching  the  earth  is  a  matter  of  hazard. 
If  his  descent  would  according  to  the  circumstances 
draw  a  crowd  of  people  around  him,  either  out  of  curi- 
osity, or  for  the  purpose  of  rescuing  him  from  a  perilous 
situation,  all  this  he  ought  to  have  foreseen,  and  must  be 
responsible  for.' 

Air  Not  Really   Free. 

"The  general  belief  among  people  is,  that  the  air  is 
free.  Not  only  free  to  breathe  and  enjoy,  but  free  to 
travel  in,  and  that  no  one  has  any  definite  jurisdiction 
over,  or  in  any  part  of  it.  Now  suppose  this  were  made  a 
legal  doctrine.  Would  a  murder  perpetrated  above  the 
clouds  have  to  go  unpunished?  Undoubtedly.  For  fel- 
onies committed  upon  the  high  seas  ample  provision  is 
made  for  their  punishment,  but  new  provisions  will  have 
to  be  made  for  crimes  committed  in  the  air. 

Relations  of  Owner  and  Employee. 

"It  is  a  general  rule  of  law  that  a  master  is  bound  to 
provide  reasonably  safe  tools,  appliances  and  machines 
for  his  servant.  How  this  rule  is  going  to  be  applied 
in  cases  of  aeroplanes,  remains  to  be  seen.  The  aero- 
plane owner  who  hires  a  professional  aeronaut,  that  is, 
one  who  has  qualified  as  an  expert,  owes  him  very  little 
legal  duty  to  supply  him  with  a  perfect  aeroplane.  The 
expert  is  supposed  to  know  as  much  regarding  the  ma- 
chine as  the  owner,  if  not  more,  and  his  acceptance  of 
his  position  relieves  the  owner  from  liability.  When 
the  owner  hires  an  amateur  aeronaut  to  run  the  aero- 


176  FLYING   MACHINES: 

plane,  and  teaches  him  how  to  manipulate  it,  even  though 
the  prescribed  manner  of  manipulation  will  make  flight 
safe,  nevertheless  if  the  machine  is  visibly  defective,  or 
known  to  be  so,  any  injury  which  results  to  the  aero- 
naut the  owner  is  liable  for. 

As  to  Aeroplane  Contracts. 

"At  the  present  time  there  are  many  orders  being 
placed  with  aeroplane  manufacturing  companies.  There 
are  some  unique  questions  to  be  raised  here  under  the 
law  of  contract.  It  is  an  elementary  principle  of  law 
that  no  one  can  be  compelled  to  complete  a  contract 
which  in  itself  is  impossible  to  perform.  For  instance, 
a  contract  to  row  a  boat  across  the  Atlantic  in  two 
weeks,  for  a  consideration,  could  never  be  enforced  be- 
cause it  is  within  judicial  knowledge  that  such  an  under- 
taking is  beyond  human  power.  Again,  contracts  formed 
for  the  doing  of  acts  contrary  to  nature  are  never  en- 
forcible,  and  here  is  where  our  difficulty  comes  in.  Is 
it  possible  to  build  a  machine  or  species  of  craft  which 
will  transport  a  person  or  goods  through  the  air?  The 
courts  know  that  balloons  are  practical ;  that  is,  they 
know  that  a  bag  filled  with  gas  has  a  lifting  power  and 
can  move  through  the  air  at  an  appreciable  height. 
Therefore,  a  contract  to  transport  a  person  in  such  man- 
ner is  a  good  contract,  and  the  conditions  being  favor- 
able could  undoubtedly  be  enforced.  But  the  passen- 
gers' right  of  action  for  injury  would  be  very  limited. 

No  Redress  for  Purchasers. 

"In  the  case  of  giving  warranties  on  aeroplanes,  we 
have  yet  to  see  just  what  a  court  is  going  to  say.  It  is 
easy  enough  for  a  manufacturer  to  guarantee  to  build  a 
machine  of  certain  dimensions  and  according  to  certain 
specifications,  but  when  he  inserts  a  clause  in  the  con* 


CONSTRUCTION   AND   OPERATION  177 

tract  to  the  effect  that  the  machine  will  raise  itself  from 
the  surface  of  the  earth,  defy  the  laws  of  gravity,  and 
soar  in  the  heavens  at  the  will  of  the  aviator,  he  is  to 
say  the  least  contracting  to  perform  a  miracle. 

"Until  aeroplanes  have  been  made  and  accepted  as 
practical,  no  court  will  force  a  manufacturer  to  turn  out 
a  machine  guaranteed  to  fly.  So  purchasers  can  well 
remember  that  if  their  machines  refuse  to  fly  they  have 
no  redress  against  the  maker,  for  he  can  always  say, 
'The  industry  is  still  in  its  experimental  stage.'  In 
contracting,  for  an  engine  no  builder  will  guarantee  that 
the  particular  engine  will  successfully  operate  the  aero- 
plane. In  fact  he  could  never  be  forced  to  live  up  to 
such  an  agreement,  should  he  agree  to  a  stipulation  of 
that  sort.  The  best  any  engine  maker  will  guarantee 
is  to  build  an  engine  according  to  specifications." 


178 


FLYING  MACHINES: 


CHAPTER  XX. 

SOARING   FLIGHT. 

By  Octave  Chanute. 

*There  is  a  wonderful  performance  daily  exhibited  in 
southern  climes  and  occasionally  seen  in  northerly 
latitudes  in  summer,  which  has  never  been  thoroughly 
explained.  It  is  the  soaring  or  sailing  flight  of  certain 
varieties  of  large  birds  who  transport  themselves  on  rigid, 
unflapping  wings  in  any  desired  direction ;  who  in  winds 
of  6  to  20  miles  per  hour,  circle,  rise,  advance,  return  and 
remain  aloft  for  hours  without  a  beat  of  wing,  save  for 
getting  under  way  or  convenience  in  various  maneuvers. 
They  appear  to  obtain  from  the  wind  alone  all  the  neces- 
sary energy,  even  to.  advancing  dead  against  that  wind. 
This  feat  is  so  much  opposed  to  our  general  ideas  of 
physics  that  those  who  have  not  seen  it  sometimes  deny 
its  actuality,  and  those  who  have  only  occasionally  wit- 
nessed it  subsequently  doubt  the  evidence  of  their  own 
eyes.  Others,  who  have  seen  the  exceptional  perform- 
ances, speculate  on  various  explanations,  but  the  majority 
give  it  up  as  a  sort  of  "negative  gravity." 

Soaring  Power  of  Birds. 

The  writer  of  this  paper  published  in  the  "Aeronautical 
Annual"  for  1896  and  1897  an  article  upon  the  sailing 
flight  of  birds,  in  which  he  gave  a  list  of  the  authors  who 


Aeronautics. 

179 


180  FLYING   MACHINES: 

had  described  such  flight  or  had  advanced  theories  for 
its  explanation,  and  he  passed  these  in  review.  He  also 
described  his  own  observations  and  submitted  some  com- 
putations to  account  for  the  observed  facts.  These  com- 
putations were  correct  as  far  as  they  went,  but  they  were 
scanty.  It  wras,  for  instance,  shown  convincingly  by 
analysis  that  a  gull  weighing  2.188  pounds,  with  a  total 
supporting  surface  of  2.015  square  feet,  a  maximum  body 
cross-section  of  0.126  square  feet  and  a  maximum  cross- 
section  of  wing  edges  of  0.098  square  feet,  patrolling  on 
rigid  wings  (soaring)  on  the  weather  side  of  a  steamer 
and  maintaining  an  upward  angle  or  attitude  of  5  degrees 
to  7  degrees  above  the  horizon,  in  a  wind  blowing  12.78 
miles  an  hour,  which  was  deflected  upward  10  degrees 
to  20  degrees  by  the  side  of  the  steamer  (these  all  being 
carefully  observed  facts),  was  perfectly  sustained  at  its 
own  "relative  speed"  of  17.88  miles  per  hour  and  ex- 
tracted from  the  upward  trend  of  the  wind  sufficient  en- 
ergy to  overcome  all  the  resistances,  this  energy 
amounting  to  6.44  foot-pounds  per  second. 

Great  Power  of  Gulls. 

It  was  shown  that  the  same  bird  in  flapping  flight  in 
calm  air,  with  an  attitude  or  incidence  of  3  degrees  to  5 
degrees  above  the  horizon  and  a  speed  of  20.4  miles  an 
hour  was  well  sustained  and  expended  5.88  foot-pounds 
per  second,  this  being  at  the  rate  of  204  pounds  sustained 
per  horsepower.  It  was  stated  also  that  a  gull  in  its  ob- 
served maneuvers,  rising  up  from  a  pile  head  on  unflap- 
ping  wings,  then  plunging  forward  against  the  wind  and 
subsequently  rising  higher  than  his  starting  point,  must 
either  time  his  ascents  and  descents  exactly  with  the  var- 
iations in  wind  velocities,  or  must  meet  a  wind  billow 
rotating  on  a  horizontal  axis  and  come  to  a  poise  on  its 
crest,  thus  availing  of  an  ascending  trend. 


CONSTRUCTION  AND    OPERATION 


181 


But  the  observations  failed  to  demonstrate  that  the 
variations  of  the  wind  gusts  and  the  movements  of  the 
bird  were  absolutely  synchronous,  and  it  was  conjectured 
that  the  peculiar  shape  of  the  soaring  wing  of  certain 
birds,  as  differentiated  from  the  flapping  wing,  might, 
when  experimented  upon,  hereafter  account  for  the  per- 
formance. 

Mystery  to  be  Explained. 

These  computations,  however  satisfactory  they  were 
for  the  speed  of  winds  observed,  failed  to  account  for  the 


Farman  Biplane  in   Flight. 

observed  spiral  soaring  of  buzzards  in  very  light  winds 
and  the  writer  was  compelled  to  confess:  "Now,  this 
spiral  soaring  in  steady  breezes  of  5  to  10  miles  per  hour 
which  are  apparently  horizontal,  and  through  which  the 
bird  maintains  an  average  speed  of  about  20  miles  an 
hour,  is  the  mystery  to  be  explained.  It  is  not  accounted 
for,  quantitatively,  by  any  of  the  theories  which  have 
been  advanced,  and  it  is  the  one  performance  which  has 
led  some  observers  to  claim  that  it  was  done  through 
'aspiration,'  i.  e.,  that  a  bird  acted  upon  by  a  current,  ac- 


182  FLYING   MACHINES: 

tually  drew  forward  into  that  current  against  its  exact 
direction  of  motion." 

Buzzards  Soar  in  Dead  Calm. 

A  still  greater  mystery  was  propounded  by  the  few 
observers  who  asserted  that  they  had  seen  buzzards  soar- 
ing in  a  dead  calm,  maintaining  their  elevation  and  their 
speed.  Among  these  observers  was  Mr.  E.  C.  Huffaker, 
at  one  time  assistant  experimenter  for  Professor  Langley. 
The  writer  believed  and  said  then  that  he  must  in  some 
way  have  been  mistaken,  yet,  to  satisfy  himself,  he  paid 
several  visits  to  Mr.  Huffaker,  in  Eastern  Tennessee  and 
took  along  his  anemometer.  He  saw  quite  a  number  of 
buzzards  sailing  at  a  height  of  75  to  100  feet  in  breezes 
measuring  5  or  6  miles  an  hour  at  the  surface  of  the 
ground,  and  once  he  saw  one  buzzard  soaring  apparently 
in  a  dead  calm. 

The  writer  was  fairly  baffled.  The  bird  was  not  simply 
gliding,  utilizing  gravity  or  acquired  momentum,  he  was 
actually  circling  horizontally  in  defiance  of  physics  and 
mathematics.  It  took  two  years  and  a  whole  series  of 
further  observations  to  bring  those  two  sciences  into 
accord  with  the  facts. 

Results  of  Close  Observations. 

Curiously  enough  the  key  to  the  performance  of  cir- 
cling in  a  light  wind  or  a  dead  calm  was  not  found 
through  the  usual  way  of  gathering  human  knowledge, 
i.  e.,  through  observations  and  experiment.  These  had 
failed  because  I  did  not  know  what  to  look  for.  The 
mystery  was,  in  fact,  solved  by  an  eclectic  process  of 
conjecture  and  computation,  but  once  these  computations 
indicated  what  observations  should  be  made,  the  results 
gave  at  once  the  reasons  for  the  circling  of  the  birds,  for 
their  then  observed  attitude,  and  for  the  necessity  of  an 


CONSTRUCTION   AND    OPERATION  183 

independent  initial  sustaining  speed  before  soaring  be- 
gan. Both  Mr.  Huffaker  and  myself  verified  the  data 
many  times  and  I  made  the  computations. 

These  observations  disclosed  several  facts : 

ist. — That  winds  blowing  five  to  seventeen  miles  per 
hour  frequently  had  rising  trends  of  10  degrees  to  15 
degrees,  and  that  upon  occasions  when  there  seemed  to  be 
absolutely  no  wind,  there  was  often  nevertheless  a  local 
rising  of  the  air  estimated  at  a  rate  of  four  to  eight  miles 
or  more  per  hour.  This  was  ascertained  by  watching 
thistledown,  and  rising  fogs  alongside  of  trees  or  hills  of 
known  height.  Everyone  will  readily  realize  that  when 
walking  at  the  rate  of  four  to  eight  miles  an  hour  in  a 
dead  calm  the  "relative  wind"  is  quite  inappreciable  to 
the  senses  and  that  such  a  rising  air  would  not  be  noticed. 

2nd. — That  the  buzzard,  sailing  in  an  apparently  dead 
horizontal  calm,  progressed  at  speeds  of  fifteen  to  eight- 
een miles  per  hour,  as  measured  by  his  shadow  on  the 
ground.  It  was  thought  that  the  air  was  then  possibly 
rising  8.8  feet  per  second,  or  six  miles  per  hour. 

3rd. — That  when  soaring  in  very  light  winds  the  angle 
of  incidence  of  the  buzzards  was  negative  to  the  horizon 
— i.  e.,  that  when  seen  coming  toward  the  eye,  the  after- 
noon light  shone  on  the  back  instead  of  on  the  breast, 
as  would  have  been  the  case  had  the  angle  been  inclined 
above  the  horizon. 

4th. — That  the  sailing  performance  only  occurred  after 
the  bird  had  acquired  an  initial  velocity  of  at  least  fifteen 
or  eighteen  miles  per  hour,  either  by  industrious  flapping 
or  by  descending  from  a  perch. 

An  Interesting  Experiment. 

5th. — That  the  whole  resistance  of  a  stuffed  buzzard, 
at  a  negative  angle  of  3  degrees  in  a  current  of  air  of 
15.52  miles  per  hour,  was  0.27  pounds.  This  test  was 


184  FLYING   MACHINES: 

kindly  made  for  the  writer  by  Professor  A.  F.  Zahm  in 
the  "wind  tunnel"  of  the  Catholic  University  at  Wash- 
ington, D.  C.,  who,  moreover,  stated  that  the  resistance 
of  a  live  bird  might  be  less,  as  the  dried  plumage  could 
not  be  made  to  lie  smooth. 

This  particular  buzzard  weighed  in  life  4.25  pounds, 
the  area  of  his  wings  and  body  was  4.57  square  feet,  the 
maximum  cross-section  of  his  body  was  o.no  square  feet, 
and  that  of  his  wing  edges  when  fully  extended  was 
0.244  square  feet. 

With  these  data,  it  became  surprisingly  easy  to  com- 
pute the  performance  with  the  coefficients  of  Lilienthal 
for  various  angles  of  incidence  and  to  demonstrate  how 
this  buzzard  could  soar  horizontally  in  a  dead  horizontal 
calm,  provided  that  it  was  not  a  vertical  calm,  and  that 
the  air  was  rising  at  the  rate  of  four  or  six  miles  per 
hour,  the  lowest  observed,  and  quite  inappreciable  with- 
out actual  measuring. 

Some  Data  on  Bird  Power. 

The  most  difficult  case  is  purposely  selected.  For  if 
we  assume  that  the  bird  has  previously  acquired  an  ini- 
tial minimum  speed  of  seventeen  miles  an  hour  (24.93 
feet  per  second,  nearly  the  lowest  measured),  and  that 
the  air  was  rising  vertically  six  miles  an  hour  (8.80  feet 
per  second),  then  we  have  as  the  trend  of  the  "relative 
wind"  encountered : 

6 
-  —  0.353,  or  tne  tangent  of  19°  26'. 

I? 

which  brings  the  case  into  the  category  of  rising  wind 
effects.  But  the  bird  was  observed  to  have  a  negative 
angle  to  the  horizon  of  about  3°,  as  near  as  could  be 
guessed,  so  that  his  angle  of  incidence  to  the  "relative 
wind"  was  reduced  to  16°  26'. 


CONSTRUCTION  AND   OPERATION  185 

The  relative  speed  of  his  soaring  was  therefore: 

Velocity  =  V  172  +  &  =  18.03  miles  per  hour. 

At  this  speed,  using  the  Langley  co-efficient  recently 
practically  confirmed  by  the  accurate  experiments  of  Mr. 
Eiffel,  the  air  pressure  would  be : 

i8.O32  X  0.00327  =  1.063  pounds  per  square  foot. 

If  we  apply  LilienthaFs  co-efficients  for  an  angle  of 
16°  26',  we  have  for  the  force  in  action : 

Normal:  4.57  X  1-063  X  0.912  =  4.42  pounds. 

Tangential:  4.57  X  1.063  X  0.074  =  —0.359  pounds, 
which  latter,  being  negative,  is  a  propelling  force. 

Results  Astonish  Scientists. 

Thus  we  have  a  bird  weighing  4.25  pounds  not  only 
thoroughly  supported,  but  impelled  forward  by  a  force 
of  0.359  pounds,  at  seventeen  miles  per  hour,  while  the 
experiments  of  Professor  A.  F.  Zahm  showed  that  the 
resistance  at  15.52  miles  per  hour  was  only  0.27  pounds, 

J72 
or  0.27  X  —  —  0.324  pounds,  at  seventeen  miles  an 

I5-522 
hour. 

These  are  astonishing  results  from  the  data  obtained, 
and  they  lead  to  the  inquiry  whether  the  energy  of  the 
rising  air  is  sufficient  to  make  up  the  losses  which  occur 
by  reason  of  the  resistance  and  friction  of  the  bird's  body 
and  wings,  which,  being  rounded,  do  not  encounter  air 
pressures  in  proportion  to  their  maximum  cross-section. 

We  have  no  accurate  data  upon  the  co-efficients  to  ap- 
ply and  estimates  made  by  myself  proved  to  be  much 
smaller  than  the  0.27  pounds  resistance  measured  by 
Professor  Zahm,  so  that  we  will  figure  with  the  latter 
as  modified.  As  the  speed  is  seventeen  miles  per  hour,  or 
24.93  feet  per  second,  we  have  for  the  work : 

Work  done,  0.324  X  24.93  —  8.07  foot  pounds  per  sec- 
ond. 


186  FLYING   MACHINES: 

Endorsed  by  Prof.  Marvin. 

Corresponding  energy  of  rising  air  is  not  sufficient  at 
four  miles  per  hour.  This  amounts  to  but  2.10  foot  pounds 
per  second,  but  if  we  assume  that  the  air  was  rising  at 
the  rate  of  seven  miles  per  hour  (10.26  feet  per  second), 
at  which  the  pressure  with  the  Langley  coefficient  would 
be  0.16  pounds  per  square  foot,  we  have  on  4.57  square 
feet  for  energy  of  rising  air:  4.57  X  0.16  X  10.26  =  7.50 
foot  pounds  per  second,  which  is  seen  to  be  still  a  little 
too  small,  but  well  within  the  limits  of  error,  in  view  of 
the  hollow  shape  of  the  bird's  wings,  which  receive 
greater  pressure  than  the  flat  planes  experimented  upon 
by  Langley. 

These  computations  were  chiefly  made  in  January, 
1899,  and  were  communicated  to  a  few  friends,  who  found 
no  fallacy  in  them,  but  thought  that  few  aviators  would 
understand  them  if  published.  They  were  then  submitted 
to  Professor  C.  F.  Marvin  of  the  Weather  Bureau,  who 
is  well  known  as  a  skillful  physicist  and  mathematician. 
He  wrote  that  they  were,  theoretically,  entirely  sound 
and  quantitatively,  probably,  as  accurate  as  the  present 
state  of  the  measurements  of  wind  pressures  permitted. 
The  writer  determined,  however,  to  withhold  publication 
until  the  feat  of  soaring  flight  had  been  performed  by 
man,  partly  because  he  believed  that,  to  ensure  safety,  it 
would  be  necessary  that  the  machine  should  be  equipped 
witli  a  motor  in  order  to  supplement  any  deficiency  in 
wind  force. 

Conditions  Unfavorable  for  Wrights. 

The  feat  would  have  been  attempted  in  1902  by  Wright 
brothers  if  the  local  circumstances  had  been  more  favor- 
able. They 'were  experimenting  on  "Kill  Devil  Hill," 
ne?.r  Kitty  Hawk,  N.  C.  This  sand  hill,  about  100  feet 
high,  is  bordered  by  a  smooth  beach  on  the  side  whence 


CONSTRUCTION  AND    OPERATION  187 

come  the  sea  breezes,  but  has  marshy  ground  at  the  back. 
Wright  brothers  were  apprehensive  that  if  they  rose  on 
the  ascending  current  of  air  at  the  front  and  began  to 
circle  like  the  birds,  they  might  be  carried  by  the  de- 
scending current  past  the  back  of  the  hill  and  land  in 
the  marsh.  Their  gliding  machine  offered  no  greater 
head  resistance  in  proportion  than  the  buzzard,  and  their 


Latham's  Antoinette  Monoplane  in  Flight. 

gliding  angles  of  descent  are  practically  as  favorable,  but 
the  birds  performed  higher  up  in  the  air  than  they. 

Langley's  Idea  of  Aviation. 

Professor  Langley  said  in  concluding  his  paper  upon 
"The  Internal  Work  of  the  Wind" : 

"The  final  application  of  these  principles  to  the  art  of 
aerodromics  seems,  then,  to  be,  that  while  it  is  not  likely 
that  the  perfected  aerodrome  will  ever  be  able  to  dis- 
pense altogether  with  the  ability  to  rely  at  intervals  on 
some  internal  source  of  power,  it  will  not  be  indispen- 
sable that  this  aerodrome  of  the  future  shall,  in  order  to 


188  FLYING  MACHINES: 

go  any  distance — even  to  circumnavigate  the  globe  with- 
out alighting — need  to  carry  a  weight  of  fuel  which 
would  enable  it  to  perform  this  journey  under  conditions 
analogous  to  those  of  a  steamship,  but  that  the  fuel  and 
weight  need  only  be  such  as  to  enable  it  to  take  care  of 
itself  in  exceptional  moments  of  calm." 

Now  that  dynamic  flying  machines  have  been  evolved 
and  are  being  brought  under  control,  it  seems  to  be 
worth  while  to  make  these  computations  and  the  suc- 
ceeding explanations  known,  so  that  some  bold  man  will 
attempt  the  feat  of  soaring  like  a  bird.  The  theory  un- 
derlying the  performance  in  a  rising  wind  is  not  new, 
it  has  been  suggested  by  Penaud  and  others,  but  it  has 
attracted  little  attention  because  the  exact  data  and  the 
maneuvers  required  were  not  known  and  the  feat  had 
not  yet  been  performed  by  a  man.  The  puzzle  has  al- 
ways been  to  account  for  the  observed  act  in  very  light 
winds,  and  it  is  hoped  that  by  the  present  selection  of 
the  most  difficult  case  to  explain — i.  e.,  the  soaring  in  a 
dead  horizontal  calm — somebody  will  attempt  the  exploit. 

Requisites  for  Soaring  Flights. 

The  following  are  deemed  to  be  the  requisites  and 
maneuvers  to  master  the  secrets  of  soaring  flight: 

1st. — Develop  a  dynamic  flying  machine  weighing 
about  one  pound  per  square  foot  of  area,  with  stable 
equilibrium  and  under  perfect  control,  capable  of  gliding 
by  gravity  at  angles  of  one  in  ten  (5^4°)  in  still  air. 

2nd. — Select  locations  where  soaring  birds  abound  and 
occasions  where  rising  trends  of  gentle  winds  are  fre- 
quent and  to  be  relied  on. 

3rd. — Obtain  an  initial  velocity  of  at  least  25  feet  per 
second  before  attempting  to  soar. 

4th. — So  locate  the  center  of  gravity  that  the  apparatus 
shall  assume  a  negative  angle,  fore  and  aft,  of  about  3°. 


CONSTRUCTION  AND   OPERATION 


189 


190  FLYING  MACHINES: 

Calculations  show,  however,  that  sufficient  propelling 
force  may  still  exist  at  o°,  but  disappears  entirely  at 
+  4°. 

5th. — Circle  like  the  bird.  Simultaneously  with  the 
steering,  incline  the  apparatus  to  the  side  toward  which 
it  is  desired  to  turn,  so  that  the  centrifugal  force  shall 
be  balanced  by  the  centripetal  force.  The  amount  of  the 
required  inclination  depends  upon  the  speed  and  on  the 
radius  of  the  circle  swept  over. 

6th. — Rise  spirally  like  the  bird.  Steer  with  the  hori- 
zontal rudder,  so  as  to  descend  slightly  when  going 
with  the  wind  and  to  ascend  when  going  against  the 
wind.  The  bird  circles  over  one  spot  because  the  rising 
trends  of  wind  are  generally  confined  to  small  areas  or 
local  chimneys,  as  pointed  out  by  Sir  H.  Maxim  and 
others. 

7th. — Once  altitude  is  gained,  progress  may  be  made 
in  any  direction  by  gliding  downward  by  gravity. 

The  bird's  flying  apparatus  and  skill  are  as  yet  infinite- 
ly superior  to  those  of  man,  but  there  are  indications  that 
within  a  few  years  the  latter  may  evolve  more  accurately 
proportioned  apparatus  and  obtain  absolute  control  over 
it. 

It  is  hoped,  therefore,  that  if  there  be  found  no  radical 
error  in  the  above  computations,  they  will  carry  the  con- 
viction that  soaring  flight  is  not  inaccessible  to  man,  as 
it  promises  great  economies  of  motive  power  in  favorable 
localities  of  rising  winds. 

The  writer  will  be  grateful  to  experts  who  may  point 
out  any  mistake  committed  in  data  or  calculations,  and 
will  furnish  additional  information  to  any  aviator  who 
may  wish  to  attempt  the  feat  of  soaring. 


CHAPTER  XXI. 

FLYING   MACHINES    VS.   BALLOONS. 

While  wonderful  success  has  attended  the  develop- 
ment of  the  dirigible  (steerable)  balloon  the  most  ardent 
advocates  of  this  form  of  aerial  navigation  admit  that  it 
has  serious  drawbacks.  Some  of  these  may  be  described 
as  follows: 

Expense  and  Other  Items. 

.Great  Initial  Expense. — The  modern  dirigible  balloon 
costs  a  fortune.  The  Zeppelin,  for  instance,  costs  more 
than  $100,000  (these  are  official  figures). 

Expense  of  Inflation. — Gas  evaporates  rapidly,  and  a 
balloon  must  be  re-inflated,  or  partially  re-inflated,  every 
time  it  is  used.  The  Zeppelin  holds  460,000  cubic  feet 
of  gas  which,  even  at  $i  per  thousand,  would  cost  $460. 

Difficulty  of  Obtaining  Gas. — If  a  balloon  suddenly 
becomes  deflated,  by  accident  or  atmospheric  conditions, 
far  from  a  source  of  gas  supply,  it  is  practically  worth- 
less. Gas  must  be  piped  to  it,  or  the  balloon  carted  to 
the  gas  house — an  expensive  proceeding  in  either  event. 

Lack  of  Speed  and  Control. 

Lack  of  Speed. — Under  the  most  favorable  conditions 
the  maximum  speed  of  a  balloon  is  30  miles  an  hour. 
Its  great  bulk  makes  the  high  speed  attained  by  flying 
machines  'impossible. 

Difficulty  of  Control. — While  the  modern  dirigible  bal- 

191 


192  FLYING  MACHINES: 

loon  is  readily  handled  in  calm  or  light  winds,  its  bulk 
makes  it  difficult  to  control  in  heavy  winds. 

The  Element  of  Danger. — Numerous  balloons  have 
been  destroyed  by  lightning  and  similar  causes.  One  of 
the  largest  of  the  Zeppelins  was  thus  lost  at  Stuttgart 
in  1908. 

Some  Balloon  Performances. 

It  is  only  a  matter  of  fairness  to  state  that,  under 
favorable  conditions,  some  very  creditable  records  have 
been  made  with  modern  balloons,  viz : 

November  23d,  1907,  the  French  dirigible  Patrie,  trav- 
elled 187  miles  in  6  hours  and  45  minutes  against  a 
light  wind.  This  was  a  little  over  28  miles  an  hour. 

The  Clement-Bayard,  another  French  machine,  sold 
to  the  Russian  government,  made  a  trip  of  125  miles  at 
a  rate  of  27  miles  an  hour. 

Zeppelin  No.  3,  carrying  eight  passengers,  and  having 
a  total  lifting  capacity  of  5,500  pounds  of  ballast  in  ad- 
dition to  passengers,  weight  of  equipment,  etc.,  was 
tested  in  October,  1906,  and  made  67  miles  in  2  hours 
and  17  minutes,  about  30  miles  an  hour. 

These  are  the  best  balloon  trips  on  record,  and  show 
forcefully  the  limitations  of  speed,  the  greatest  being  not 
over  30  miles  an  hour. 

Speed  of  Flying  Machines. 

Opposed  to  the  balloon  performances  we  have  flying 
machine  trips  (of  authentic  records)  as  follows : 

Bleriot — monoplane — in  1908 — 52  miles  an  hour. 

Delagrange — June  22,  1908 — ioj^  miles  in  16  minutes, 
approximately  42  miles  an  hour. 

Wrights — October,  1905 — the  machine  was  then  in  its 
infancy — 24  miles  in  38  minutes,  approximately  44  miles 
an  hour.  On  December  31,  1908,  the  Wrights  made  77 
miles  in  2  hours  and  20  minutes. 


CONSTRUCTION   AND    OPERATION  193 

Lambert,  a  pupil  of  the  Wrights,  and  using  a  Wright 
biplane,  on  October  18,  1909,  covered  29.82  miles  in  49 
minutes  and  39  seconds,  being  at  the  rate  of  36  miles 
an  hour.  This  flight  was  made  at  a  height  of  1,312  feet. 

Latham — October  21,  1909 — made  a  short  flight,  about, 
ii  minutes,  in  the  teeth  of  a  40  mile  gale,  at  Blackpool, 
Eng.  He  used  an  Antoniette  monoplane,  and  the  official 
report  says :  "This  exhibition  of  nerve,  daring  and  ability 
is  unparalled  in  the  history  of  aviation." 

Farman — October  20,  1909 — was  in  the  air  for  I  hour, 
32  min.,  16  seconds,  travelling  47  miles,  1,184  yards,  a 
duration  record  for  England. 

Paulhan — January  18,  1910 — 47^  miles  at  the  rate  of 
45  miles  an  hour,  maintaining  an  altitude  of  from  1,000 
to  2,000  feet. 

Expense  of  Producing  Gas. 

Gas  is  indispensable  in  the  operation  of  dirigible  bal- 
loons, and  gas  is  expensive.  Besides  this  it  is  not  always 
possible  to  obtain  it  in  sufficient  quantities  even  in  large 
cities,  as  the  supply  on  hand  is  generally  needed  for 
regular  customers.  Such  as  can  be  had  is  either  water 
or  coal  gas,  neither  of  which  is  as  efficient  in  lifting 
power  as  hydrogen. 

Hydrogen  is  the  lightest  and  consequently  the  most 
buoyant  of  all  known  gases.  It  is  secured  commercially 
by  treating  zinc  or  iron  with  dilute  sulphuric  or  hy- 
drochloric acid.  The  average  cost  may  be  safely  placed 
at  $10  per  1,000  feet  so  that,  to  inflate  a  balloon  of  the 
size  of  the  Zeppelin,  holding  460,000  cubic  feet,  would 
cost  $4,600. 

Proportions  of  Materials  Required. 

In  making  hydrogen  gas  it  is  customary  to  allow  20 
per  cent  for  loss  between  the  generation  and  the  intro- 
duction of  the  gas  into  the  balloon.  Thus,  while  the 


13 


194  FLYING   MACHINES: 

formula  calls  for  iron  28  times  heavier  than  the  weight 
of  the  hydrogen  required,  and  acid  49  times  heavier,  the 
real  quantities  are  20  per  cent  greater.  Hydrogen  weighs 
about  0.09  ounce  to  the  cubic  foot.  Consequently  if  we 
need  say  450,000  cubic  feet  of  gas  we  must  have  2,531.25 
pounds  in  weight.  To  produce  this,  allowing  for  the  20 
percent  loss,  we  must  have  35  times  its  weight  in  iron, 
or  over  44  tons.  Of  acid  it  would  take  60  times  the 
weight  of  the  gas,  or  nearly  76  tons. 

In  Time  of  Emergency. 

These  figures  are  appalling,  and  under  ordinary  con- 
ditions would  be  prohibitive,  but  there  are  times  when 
the  balloon  operator,  unable  to  obtain  water  or  coal  gas, 
must  foot  the  bills.  In  military  maneuvers,  where  the 
field  of  operation  is  fixed,  it  is  possible  to  furnish  sup- 
plies of  hydrogen  gas  in  portable  cylinders,  but  on  long 
trips  where  sudden  leakage  or  other  cause  makes  descent 
in  an  unexpected  spot  unavoidable,  it  becomes  a  question 
of  making  your  own  hydrogen  gas  or  deserting  the  bal- 
loon. And  when  this  occurs  the  balloonist  is  up  against 
another  serious  proposition — can  he  find  the  necessary 
zinc  or  iron?  Can  he  get  the  acid? 

Balloons  for  Commercial  Use. 

Despite  all  this  the  balloon  has  its  uses.  If  there  is  to 
be  such  a  thing  as  aerial  navigation  in  a  commercial 
way — the  carrying  of  freight  and  passengers — it  will 
come  through  the  employment  of  such  monster  balloons 
as  Count  Zeppelin  is  building.  But  even  then  the  carry- 
ing capacity  must  of  necessity  be  limited.  The  latest 
Zeppelin  creation,  a  monster  in  size,  is  450  feet  long, 
and  425^  feet  in  diameter.  The  dimensions  are  such  as 
to  make  all  other  balloons  look  like  pigmies ;  even  many 
ocean-going  steamers  are  much  smaller,  and  yet  its  pas- 


CONSTRUCTION  AND    OPERATION 


195 


196  FLYING   MACHINES: 

senger  capacity  is  very  small.  On  its  36-hour  flight  in 
May,  1909,  the  Zeppelin,  carried  only  eight  passengers. 
The  speed,  however,  was  quite  respectable,  850  miles 
being  covered  in  the  36  hours,  a  trifle  over  23  miles  an 
hour.  The  reserve  buoyancy,  that  is  the  total  lifting 
capacity  aside  from  the  weight  of  the  airship  and  its 
equipment,  is  estimated  at  three  tons. 


CHAPTER  XXII. 

PROBLEMS  OF  AERIAL  FLIGHT. 

In  a  lecture  before  the  Royal  Society  of  Arts,  reported 
in  Engineering,  F.  W.  Lanchester  took  the  position  that 
practical  flight  was  not  the  abstract  question  which  some 
apparently  considered  it  to  be,  but  a  problem  in  loco- 
motive engineering.  The  flying  machine  was  a  loco- 
motive appliance,  designed  not  merely  to  lift  a  weight, 
but  to  transport  it  elsewhere,  a  fact  which  should  be  suffi- 
ciently obvious.  Nevertheless  one  of  the  leading  scientific 
men  of  the  day  advocated  a  type  in  which  this,  the 
main  function  of  the  flying  machine,  was  overlooked. 
When  the  machine  was  considered  as  a  method  of  trans- 
port, the  vertical  screw  type,  or  helicopter,  became  at 
once  ridiculous.  It  had,  nevertheless,  many  advocates 
who  had  some  vague  and  ill-defined  notion  of  subsequent 
motion  through  the  air  after  the  weight  was  raised. 

Helicopter  Type  Useless. 

When  efficiency  of  transport  was  demanded,  the  heli- 
copter type  was  entirely  out  of  court.  Almost  all  of 
its  advocates  neglected  the  effect  of  the  motion  of  the 
machine  through  the  air  on  the  efficiency  of  the  ver- 
tical screws.  They  either  assumed  that  the  motion  was 
so  slow  as  not  to  matter,  or  that  a  patch  of  still  air  accom- 
panied the  machine  in  its  flight.  Only  one  form  of  this 
type  had  any  possibility  of  success.  In  this  there  were 
two  screws  running  on  inclined  axles — one  on  each  side 
of  the  weight  to  be  lifted.  The  action  of  such  inclined 
screw  was  curious,  and  in  a  previous  lecture  he  had 

197 


198  FLYING   MACHINES: 

pointed  out  that  it  was  almost  exactly  the  same  as  that 
of  a  bird's  wing.  In  high-speed  racing  craft  such  in- 
clined screws  were  of  necessity  often  used,  but  it  was 
at  a  sacrifice  of  their  efficiency.  In  any  case  the  effi- 
ciency of  the  inclined-screw  helicopter  could  not  com- 
pare with  that  of  an  aeroplane,  and  that  type  might  be 
dismissed  from  consideration  so  soon  as  efficiency  be- 
came the  ruling  factor  of  the  design. 

Must  Compete  With  Locomotive. 

To  justify  itself  the  aeroplane  must  compete,  in  some 
regard  or  other,  with  other  locomotive  appliances,  per- 
forming one  or  more  of  the  purposes  of  locomotion  more 
efficiently  than  existing  systems.  It  would  be  no  use 
unless  able  to  stem  air  currents,  so  that  its  velocity  must 
be  greater  than  that  of  the  worst  winds  liable  to  be  en- 
countered. To  illustrate  the  limitations  imposed  on  the 
motion  of  an  aeroplane  by  wind  velocity,  Mr.  Lanchester 
gave  the  diagrams  shown  in  Figs.  I  to  4.  The  circle 
in  each  case  was,  he  said,  described  with  a  radius  equal 
to  the  speed  of  the  aeroplane  in  still  air,  from  a  center 
placed  "down-wind"  from  the  aeroplane  by  an  amount 
equal  to  the  velocity  of  the  wind. 

Fig.  I  therefore  represented  the  case  in  which  the 
air  was  still,  and  in  this  case  the  aeroplane  represented 
by  A  had  perfect  liberty  of  movement  in  any  direction 

In  Fig.  2  the  velocity  of  the  wrind  was  half  that  of  the 
aeroplane,  and  the  latter  could  still  navigate  in  any 
direction,  but  its  speed  against  the  wind  was  only  one- 
third  of  its  speed  with  the  wind. 

In  Fig.  3  the  velocity  of  the  wind  was  equal  to  that 
of  the  aeroplane,  and  then  motion  against  the  wind  was 
impossible ;  but  it  could  move  to  any  point  of  the 
circle,  but  not  to  any  point  lying  to  the  left  of  the  tan- 
gent A  B.  Finally,  when  the  wind  had  a  greater 


CONSTRUCTION  AND    OPERATION 


199 


speed  than  the  aeroplane,  as  in  Fig.  4,  the  machine  could 
move  only  in  directions  limited  by  the  tangents  A  C 
and  A  D. 

Matter  of  Fuel  Consumption. 

Taking  the  case  in  which  the  wind  had  a  speed  equal 
to  half  that  of  the  aeroplane,  Mr.  Lanchester  said  that 
for  a  given  journey  out  and  home,  down  wind  and  back, 
the  aeroplane  would  require  30  per  cent  more  fuel  than 
if  the  trip  were  made  in  still  air;  while  if  the  journey 


was  made  at  right  angles  to  the  direction  of  the  wind, 
the  fuel  needed  would  be  15  per  cent  more  than  in  a 
calm.  This  30  per  cent  extra  was  quite  a  heavy  enough 
addition  to  the  fuel ;  and  to  secure  even  this  figure  it 
was  necessary  that  the  aeroplane  should  have  a  speed  of 
twice  that  of  the  maximum  wind  in  which  it  was  desired 
to  operate  the  machine.  Again,  as  stated  in  the  last 
lecture,  to  insure  the  automatic  stability  of  the  machine 
it  was  necessary  that  the  aeroplane  speed  should  be 
largely  in  excess  of  that  of  the  gusts  of  wind  liable  to 
be  encountered. 


200  FLYING   MACHINES: 

Eccentricities  of  the  Wind. 

There  was,  Mr.  Lanchester  said,  a  loose  connection 
between  the  average  velocity  of  the  wind  and  the  max- 
imum speed  of  the  gusts.  When  the  average  speed  of 
the  wind  was  40  miles  per  hour,  that  of  the  gusts  might 
be  equal  or  more.  At  one  moment  there  might  be  a 
calm  or  the  direction  of  the  wind  even  reversed,  followed, 
the  next  moment,  by  a  violent  gust.  About  the  same 
minimum  speed  was  desirable  for  security  against  gusts 
as  was  demanded  by  other  considerations.  Sixty  miles 
an  hour  was  the  least  figure  desirable  in  an  aeroplane, 
and  this  should  be  exceeded  as  much  as  possible.  Ac- 
tually, the  Wright  machine  had  a  speed  of  38  miles  per 
hour,  while  Farman's  Voisin  machine  flew  at  45  miles 
per  hour. 

Both  machines  were  extremely  sensitive  to  high  winds, 
and  the  speaker,  in  spite  of  newspaper  reports  to  the 
contrary,  had  never  seen  either  flown  in  more  than  a 
gentle  breeze.  The  damping  out  of  the  oscillations  of 
the  flight  path,  discussed  in  the  last  lecture,  increased 
with  the  fourth  power  of  the  natural  velocity  of  flight, 
and  rapid  damping  formed  the  easiest,  and  sometimes 
the  only,  defense  against  dangerous  oscillations.  A 
machine  just  stable  at  35  miles  per  hour  would  have 
reasonably  rapid  damping  if  its  speed  were  increased  to 
60  miles  per  hour. 

Thinks  Use  Is  Limited. 

It  was,  the  lecturer  proceeded,  inconceivable  that  any 
very  extended  use  should  be  made  of  the  aeroplane  unless 
the  speed  was  much  greater  than  that  of  the  motor  car. 
It  might  in  special  cases  be  of  service,  apart  from  this 
increase  of  speed,  as  in  the  exploration  of  countries 
destitute  of  roads,  but  it  would  have  no  general  utility. 
With  an  automobile  averaging  25  to  35  miles  per  hour, 


CONSTRUCTION   AND    OPERATION  201 

almost  any  part  of  Europe,  Russia  excepted,  was  at- 
tainable in  a  day's  journey.  A  flying  machine  of  but 
equal  speed  would  have  no  advantages,  but  if  the  speed 
could  be  raised  to  90  or  100  miles  per  hour,  the  whole 
continent  of  Europe  would  become  a  playground,  every 
part  being  within  a  daylight  flight  of  Berlin.  Further, 
some  marine  craft  now  had  speeds  of  40  miles  per  hour, 
and  efficiently  to  follow  up  and  report  movements  of 
such  vessels  an  aeroplane  should  travel  at  60  miles  per 
hour  at  least.  Hence  from  all  points  of  view  appeared 
the  imperative  desirability  of  very  high  velocities  of 
flight.  The  difficulties  of  achievement  were,  however, 
great. 

Weight  of  Lightest  Motors. 

As  shown  in  the  first  lecture  of  his  course,  the  resist- 
ance to  motion  was  nearly  independent  of  the  velocity, 
so  that  the  total  work  done  in  transporting  a  given 
weight  was  nearly  constant.  Hence  the  question  of  fuel 
economy  was  not  a  bar  to  high  velocities  of  flight,  though 
should  these  become  excessive,  the  body  resistance  might 
constitute  a  large  proportion  of  the  total.  The  horse- 
power required  varied  as  the  velocity,  so  the  factor  gov- 
erning the  maximum  velocity  of  flight  was  the  horse- 
power that  could  be  developed  on  a  given  weight.  At 
present  the  weight  per  horsepower  of  feather-weight 
motors  appeared  to  range  from  2%  pounds  up  to  7 
pounds  per  brake  horsepower,  some  actual  figures  being 
as  follows : 

Antoinette    , 5  Ibs. 

Eiat   3  Ibs. 

Gnome Under  3  Ibs. 

Metallurgic    8  Ibs. 

Renault    7  Ibs. 

Wright   6  Ibs. 


202  FLYING   MACHINES: 

Automobile  engines,  on  the  other  hand,  commonly 
weighed  12  pounds  to  13  pounds  per  brake  horsepower. 

For  short  flights  fuel  economy  was  of  less  importance 
than  a  saving  in  the  weight  of  the  engine.  For  long 
flights,  however,  the  case  was  different.  Thus,  if  the 
gasolene  consumption  was  J^  pound  per  horsepower  hour, 
and  the  engine  weighed  3  pounds  per  brake  horsepower, 
the  fuel  needed  for  a  six-hour  flight  would  weigh  as  much 
as  the  engine,  but  for  half  an  hour's  flight  its  weight 
would  be  unimportant. 

Best  Means  of  Propulsion. 

The  best  method  of  propulsion  was  by  the  screw, 
which  acting  in  air  was  subject  to  much  the  same  con- 
ditions as  obtained  in  marine  work.  Its  efficiency  de- 
pended on  its  diameter  and  pits  and  on  its  position, 
whether  in  front  of  or  behind  the  body  propelled.  From 
this  theory  of  dynamic  support,  Mr.  Lanchester  pro- 
ceeded, the  efficiency  of  each  element  of  a  screw  pro- 
peller could  be  represented  by  curves  such  as  were  given 
in  his  first  lecture  before  the  society,  and  from  these 
curves  the  over-all  efficiency  of  any  proposed  propeller 
could  be  computed,  by  mere  inspection,  with  a  fair  de- 
gree of  accuracy.  These  curves  showed  that  the  tips  of 
long-bladed  propellers  were  inefficient,  as  was  also  the 
portion  of  the  blade  near  the  root.  In  actual  marine 
practice  the  blade  from  boss  to  tip  was  commonly  of 
such  a  length  that  the  over-all  efficiency  was  95  per  cent 
of  that  of  the  most  efficient  element  of  it. 

Advocates  Propellers  in  Rear. 

From  these  curves  the  diameter  and  appropriate  pitch 
of  a  screw  could  be  calculated,  .and  the  number  of  rev- 
olutions was  then  fixed.  Thus,  for  a  speed  of  80  feet 
per  second  the  pitch  might  come  out  as  8  feet,  in  which 


CONSTRUCTION   AND    OPERATION  203 

case  the  revolutions  would  be  600  per  minute,  which 
might,  however,  be  too  low  for  the  motor,  it  was  then 
necessary  either  to  gear  down  the  propeller,  as  was  done 
in  the  Wright  machine,  or,  if  it  was  decided  to  drive  it 
direct,  to  sacrifice  some  of  the  efficiency  of  the  propeller. 
An  analogous  case  arose  in  the  application  of  the  steam 
turbine  to  the  propulsion  of  cargo  boats,  a  problem  as 
yet  unsolved.  The  propeller  should  always  be  aft,  so 
that  it  could  abstract  energy  from  the  wake  current,  and 
also  so  that  its  wash  was  clear  of  the  body  propelled. 
The  best  possible  efficiency  was  about  70  per  cent,  and 
it  was  safe  to  rely  upon  66  per  cent. 

Benefits   of   Soaring   Flight. 

There  was,  Mr.  Lanchester  proceeded,  some  possibility 
of  the  aeronaut  reducing  the  power  needed  for  transport 
by  his  adopting  the  principle  of  soaring  flight,  as  exem- 
plified by  some  birds.  There  were,  he  continued,  two 
different  modes  of  soaring  flight.  In  the  one  the  bird 
made  use  of  the  upward  current  of  air  often  to  be  found 
in  the  neighborhood  of  steep  vertical  cliffs.  These  cliffs 
deflected  the  air  upward  long  before  it  actually  reached 
the  cliff,  a  whole  region  below  being  thus  the  seat  of 
an  upward  current.  Darwin  has  noted  that  the  condor 
was  only  to  be  found  in  the  neighborhood  of  such  cliffs. 
Along  the  south  coast  also  the  gulls  made  frequent  use 
of  the  up  currents  due  to  the  nearly  perpendicular  chalk 
cliffs  along  the  shore. 

In  the  tropics  up  currents  were  also  caused  by  tem- 
perature differences.  Cumulus  clouds,  moreover,  were 
nearly  always  the  terminations  of  such  up  currents  of 
heated  air,  which,  on  cooling  by  expansion  in  the  upper 
regions,  deposited  their  moisture  as  fog.  These  clouds 
might,  perhaps,  prove  useful  in  the  future  in  showing 
the  aeronaut  where  up  currents  were  to  be  found.  An- 


204  FLYING   MACHINES: 

other  mode  of  soaring  flight  was  that  adopted  by  the 
albatross,  which  took  advantage  of  the  fact  that  the  air 
moved  in  pulsations,  into  which  the  bird  fitted  itself, 
being  thus  able  to  extract  energy  from  the  wind. 
Whether  it  would  be  possible  for  the  aeronaut  to  employ 
a  similar  method  must  be  left  to  the  future  to  decide. 

Main  Difficulties  in  Aviation. 

In  practical  flight  difficulties  arose  in  starting  and  in 
alighting.  There  was  a  lower  limit  to  the  speed  at 
which  the  machine  was  stable,  and  it  was  inadvisable  to 
leave  the  ground  till  this  limit  was  attained.  Similarly, 
in  alighting  it  was  inexpedient  to  reduce  the  speed  below 
the  limit  of  stability.  This  fact  constituted  a  difficulty 
in  the  adoption  of  high  speeds,  since  the  length  of  run 
needed  increased  in  proportion  to  the  square  of  the 
velocit}7".  This  drawback  could,  however,  be  surmounted 
by  forming  starting  and  alighting1  grounds  of  ample  size. 
He  thought  it  quite  likely  in  the  future  that  such  grounds 
would  be  considered  as  essential  to  the  flying  machine 
as  a  seaport  was  to  an  ocean-going  steamer  or  as  a  road 
was  to  the  automobile. 

Requisites   of  Flying   Machine. 

Flying  machines  were  commonly  divided  into  mono- 
planes and  biplanes,  according  as  they  had  one  or  two 
supporting  surfaces.  The  distinction  was  not,  however, 
fundamental.  To  get  the  requisite  strength  some  form 
of  girder  framework  was  necessary,  and  it  was  a  mere 
question  of  convenience  whether  the  supporting  surface 
was  arranged  along  both  the  top  and  the  bottom  of  this 
girder,  or  along  the  bottom  only.  The  framework  adopted 
universally  was  of  wood  braced  by  ties  of  pianoforte 
wire,  an  arrangement  giving  the  stiffness  desired  with 
the  least  possible  weight.  Some  kind  of  chassis  was  also 
necessary. 


CHAPTER  XXIII. 

AMATEURS  MAY  USE  WRIGHT  PATENTS. 

Owing-  to  the  fact  that  the  Wright  brothers  have  en- 
joined a  number  of  professional  aviators  from  using 
their  system  of  control,  amateurs  have  been  slow  to 
adopt  it.  They  recognize  its  merits,  and  would  like  to 
use  the  system,  but  have  been  apprehensive  that  it 
might  involve  them  in  litigation.  There  is  no  danger 
of  this,  as  will  be  seen  by  the  following  statement  made 
by  the  Wrights : 

What  Wright  Brothers  Say. 

"Any  amateur,  any  professional  who  is  not  exhibiting 
for  money,  is  at  liberty  to  use  our  patented  devices. 
We  shall  be  glad  to  have  them  do  so,  and  there  will  be 
no  interference  on  our  part,  by  legal  action,  or  otherwise. 
The  only  men  we  proceed  against  are  those  who,  with- 
out our  permission,  without  even  asking  our  consent, 
coolly  appropriate  the  results  of  our  labors  and  use  them 
for  the  purpose  of  making  money.  Curtiss,  Delagrange, 
Voisin,  and  all  the  rest  of  them  who  have  used  our 
devices  have  done  so  in  money-making  exhibitions.  So 
long  as  there  is  any  money  to  be  made  by  the  use  of  the 
products  of  our  brains,  we  propose  to  have  it  ourselves. 
It  is  the  only  way  in  which  we  can  get  any  return  for 
the  years  of  patient  work  we  have  given  to  the  problem 
of  aviation.  On  the  other  hand,  any  man  who  wants 
to  use  these  devices  for  the  purpose  of  pleasure,  or  the 
advancement  of  science,  is  welcome  to  do  so,  without 
money  and  without  price.  This  is  fair  enough,  is  it  not?" 

205 


206  PLYING   MACHINES: 

Basis  of  the  Wright  Patents. 

In  a  flying"  machine  a  normally  flat  aeroplane  having 
lateral  marginal  portions  capable  of  movement  to  dif- 
ferent positions  above  or  below  the  normal  plane  of  the 
body  of  the  aeroplane,  such  movement  being  about  an 
axis  transverse  to  the  line  of  flight,  whereby  said  lateral 
marginal  portions  may  be  moved  to  different  angles  rel- 
atively to  the  normal  plane  of  the  body  of  the  aero- 
plane, so  as  to  present  to  the  atmosphere  different  angles 
of  incidence,  and  means  for  so  moving  said  lateral  mar- 
ginal portions,  substantially  as  described. 

Application  of  vertical  struts  near  the  ends  having 
flexible  joints. 

Means  for  simultaneously  imparting  such  movement 
to  said  lateral  portions  to  different  angles  relatively  to 
each  other. 

Refers  to  the  movement  of  the  lateral  portions  on  the 
same  side  to  the  same  angle. 

Means  for  simultaneously  moving  vertical  rudder  so 
as  to  present  to  the  wind  that  side  thereof  nearest  the 
side  of  the  aeroplane  having  the  smallest  angle  of  in- 
cidence. 

Lateral  stability  is  obtained  by  warping  the  end  wings 
by  moving  the  lever  at  the  right  hand  of  the  operator, 
connection  being  made  by  wires  from  the  lever  to  the 
wing  tips.  The  rudder  may  also  be  curved  or  warped  in 
similar  manner  by  lever  action. 

Wrights  Obtain  an  Injunction. 

In  January,  1910,  Judge  Hazel,  of  the  United  States 
Circuit  Court,  granted  a  preliminary  injunction  restrain- 
ing the  Herring-Curtiss  Co.,  and  Glenn  H.  Curtiss,  from 
manufacturing,  selling,  or  using  for  exhibition  purposes 
the  machine  known  as  the  Curtiss  aeroplane.  The  in- 
junction was  obtained  on  the  ground  that  the  Curtiss 


CONSTRUCTION  AND    OPERATION 


207 


machine  is  an  infringement  upon  the  Wright  patents  in 
the  matter  of  wing  warping  and  rudder  control. 

It  is  not  the  purpose  qf  the  authors  to  discuss  the  sub- 
ject pro  or  con.  Such  discussion  would  have  no  proper 
place  in  a  volume  of  this  kind.  It  is  enough  to  say  that 
Curtiss  stoutly  insists  that  his  machine  is  not  an  in- 
fringement of  the  Wright  patents,  although  Judge  Hazel 
evidently  thinks  differently. 

What  the  Judge  Said. 

In  granting  the  preliminary  injunction  the  judge  said: 

''Defendants    claim    generally    that    the    difference    in 

construction  of  their  apparatus  causes  the  equilibrium  or 

lateral  balance  to  be  maintained  and  its  aerial  movement 


From    Aeronautics. 

Basis    of   the    Wright    Patents. 

Moving  the  hand  lever  F,  operates  the  small  upright  lever 
E.  This  raises  the  wire  I,  which  connects  with  wires  I,  I,  run- 
ning to  tops  of  the  end  stanchions.  The  strain  depresses,  or 
warps  both  top  and  lower  planes.  Wires  H,  H,  connected  as 
shown  by  dotted  line,  operate  automatically;  as  one  end  of  the 
plane  is  depressed  the  other  is  elevated,  as  shown  in  drawing. 

secured  upon  an  entirely  different  principle  from  that 
of  complainant ;  the  defendants'  aeroplanes  are  curved, 
firmly  attached  to  the  stanchions  and  hence  are  incapable 
of  twisting  or  turning  in  any  direction;  that  the  sup- 
plementary planes  or  so-called  rudders  are  secured  to 
the  forward  stanchion  at  the  extreme  lateral  ends  of 
the  planes  and  are  adjusted  midway  between  the  upper 


208  FLYING   MACHINES: 

and  lower  planes  with  the  margins  extending  beyond  the 
edges ;  that  in  moving  the  supplementary  planes  equal 
and  uniform  angles  of  incidence  are  presented  as  distin- 
guished from  fluctuating  angles  of  incidence.  Such 
claimed  functional  effects,  however,  are  strongly  con- 
tradicted by  the  expert  witness  for  complainant. 

Similar  to  Plan  of  Wrights. 

"Upon  this  contention  it  is  sufficient  to  say  that  the 
affidavits  for  the  complainant  so  clearly  define  the 
principle  of  operation  of  the  flying  machines  in  question 
that  I  am  reasonably  satisfied  that  there  is  a  variableness 
of  the  angle  of  incidence  in  the  machine  of  defendants 
which  is  produced  when  a  supplementary  plane  on  one 
side  is  tilted  or  raised  and  the  other  stimultaneously 
tilted  or  lowered.  I  am  also  satisfied  that  the  rear 
rudder  is  turned  by  the  operator  to  the  side  having  the 
least  angle  of  incidence  and  that  such  turning  is  done 
at  the  time  the  supplementary  planes  are  raised 
or  depressed  to  prevent  tilting  or  upsetting  the  machine. 
On  the  papers  presented  I  incline  to  the  view,  as  already 
indicated,  that  the  claims  of  the  patent  in  suit  should  be 
broadly  construed ;  and  when  given  such  construction, 
the  elements  of  the  Wright  machine  are  found  in  defend- 
ants' machine  performing  the  same  functional  result. 
There  are  dissimilarities  in  the  defendants'  structure — 
changes  of  form  and  strengthening  of  parts — which  may 
be  improvements,  but  such  dissimilarities  seem  to  me  to 
have  no  bearing  upon  the  means  adopted  to  preserve  the 
equilibrium,  which  means  are  the  equivalent  of  the  claims 
in  suit  and  attain  an  identical  result. 

Variance  From  Patent  Immaterial. 

"Defendants  further  contend  that  the  curved  or  arched 
surfaces  of  the  Wright  aeroplanes  in  commercial  use  are 


» 


CONSTRUCTION  AND    OPERATION  209 

departures  from  the  patent,  which  describes  'substan- 
tially flat  surfaces/  and  that  such  a  construction  would 
be  wholly  impracticable.  The  drawing,  Fig.  3,  however, 
attached  to  the  specification,  shows  a  curved  line  inward 
of  the  aeroplane  with  straight  lateral  edges,  and  con- 
sidering such  drawing  with  the  terminology  of  the  spec- 
ification, the  slight  arching  of  the  surface  is  not  thought 
a  material  departure ;  at  any  rate,  the  patent  in  issue 
does  not  belong  to  the  class  of  patents  which  requires 
narrowing  to  the  details  of  construction." 

"June    Bug"    First   Infringement. 

Referring  to  the  matter  of  priority,  the  judge  said: 
"Indeed,  no  one  interfered  with  the  rights  of  the  pat- 
entees by  constructing  machines  similar  to  theirs  until 
in  July,  1908,  when  Curtiss  exhibited  a  flying  machine 
which  he  called  the  'June  Bug.'  He  was  immediately 
notified  by  the  patentees  that  such  machine  with  its 
movable  surfaces  at  the  tips  of  wings  infringed  the  pat- 
ent in  suit,  and  he  replied  that  he  did  not  intend  to  pub- 
licly exhibit  the  machine  for  profit,  but  merely  was  en- 
gaged in  exhibiting  it  for  scientific  purposes  as  a  member 
of  the  Aerial  Experiment  Association.  To  this  the  pat- 
entees did  not  object.  Subsequently,  however,  the  ma- 
chine, with  supplementary  planes  placed  midway  between 
the  upper  and  lower  aeroplanes,  was  publicly  exhibited 
by  the  defendant  corporation  and  used  by  Curtiss  in 
aerial  flights  for  prizes  and  emoluments.  It  further  ap- 
pears that  the  defendants  now  threaten  to  continue  such 
use  for  gain  and  profit,  and  to  engage  in  the  manufacture 
and  sale  of  such  infringing  machines,  thereby  becoming 
an  active  rival  of  complainant  in  the  business  of  con- 
structing flying  machines  embodying  the  claims  in  suit, 
but  such  use  of  the  infringing  machines  it  is  the  duty 
of  this  court,  on  the  papers  presented,  to  enjoin. 


210  FLYING   MACHINES: 

"The  requirements  in  patent  causes  for  the  issuance 
of  an  injunction  pendente  lite — the  validity  of  the  pat- 
ent, general  acquiescence  by  the  public  and  infringement 
by  the  defendants — are  so  reasonably  clear  that  I  believe 
if  not  probable  the  complainant  may  succeed  at  final 
hearing,  and  therefore,  status  quo  should  be  pre- 
served and  a  preliminary  injunction  granted. 

"So  ordered." 

Points  Claimed  By  Curtiss. 

That  the  Herring-Curtiss  Co.  will  appeal  is  a  cer- 
tainty. Mr.  Emerson  R.  Newell,  counsel  for  the  com- 
pany, states  its  case  as  follows : 

"The  Curtiss  machine  has  two  main  supporting  sur- 
faces, both  of  which'  are  curved  *  *  *  and  are  absolutely 
rigid  at  all  times  and  cannot  be  moved,  warped  or  dis- 
torted in  any  manner.  The  front  horizontal  rudder  is 
used  for  the  steering  up  or  down,  and  the  rear  vertical 
rudder  is  used  only  for  steering  to  the  right  or  left,  in 
the  same  manner  as  a  boat  is  steered  by  its  rudder.  The 
machine  is  provided  at  the  rear  with  a  fixed  horizontal 
surface,  which  is  not  present  in  the  machine  of  the  pat- 
ent, and  which  has  a  distinct  advantage  in  the  operation 
of  defendants'  machine,  as  will  be  hereafter  discussed. 

Does  Not  Warp  Main  Surface. 

"Defendants'  machine  does  not  use  the  warping  of  the 
main  supporting  surfaces  in  restoring  the  lateral  equilib- 
rium, but  has  two  comparatively  small  pivoted  balanc- 
ing surfaces  or  rudders.  When  one  end  of  the  machine 
is  tipped  up  or  down  from  the  normal,  these  planes  may 
be  thrown  in  opposite  directions  by  the  operator,  and 
so  steer  each  end  of  the  machine  up  or  down  to  its 
normal  level,  at  which  time  tension  upon  them  is  re- 
leased and  they  are  moved  back  by  the  pressure  of  the 
wind  to  their  normal  position. 


CONSTRUCTION  AND    OPERATION  211 

Rudder  Used  Only  For  Steering. 

"When  defendants'  balancing  surfaces  are  moved  they 
present  equal  angles  of  incidence  to  the  normal  rush 
of  air  and  equal  resistances,  at  each  side  of  the  machine, 
and  there  is  therefore  no  tendency  to  turn  around  a 
vertical  axis  as  is  the  case  of  the  machine  of  the  patent, 
consequently  no  reason  or  necessity  for  turning  the  ver- 
tical rear  rudder  in  defendants'  machine  to  counteract  any 
such  turning  tendency.  At  any  rate,  whatever  may  be 
the  theories  in  regard  to  this  matter,  the  fact  is  that 
the  operator  of  defendants'  machine  does  not  at  any 
time  turn  his  vertical  rudder  to  counteract  any  turning 
tendency  due  to  the  side  balancing  surfaces,  but  only 
uses  it  to  stear  the  machine  the  same  as  a  boat  is 
steered." 

Aero  Club  Recognizes  .Wrights. 

The  Aero  Club  of  America  has  officially  recognized 
the  Wright  patents.  This  course  was  taken  following  a 
conference  held  April  Qth,  1910,  participated  in  by  Will- 
iam Wright  and  Andrew  Freedman,  representing  the 
Wright  Co.,  and  the  Aero  Club's  committee,  of  Philip 
T.  Dodge,  W.  W.  Miller,  L.  L.  Gillespie,  Wm.  H.  Page 
and  Cortlandt  F.  Bishop. 

At   this   meeting  arrangements   were   made   by   which 
the  Aero  Club  recognizes   the  Wright  patents  and  will' 
not  give  its  saction  to  any  open   meet   where  the  pro- 
moters  thereof   have   not   secured    a    license    from    the 
Wright   Company 

The  substance  of  the  agreement  wras  that  the  Aero 
Club  of  America  recognizes  the  rights  of  the  owners  of 
the  Wright  patents  under  the  decisions  of  the  Federal 
courts  and  refuses  to  countenance  the  infringement  of 
those  patents  as  long  as  these  decisions  remain  in  force. 

In  the  meantime,  in  order  to  encourage  aviation,  both 
at  home  and  abroad,  and  in  order  to  permit  foreign 


212  FLYING   MACHINES: 

aviators  to  take  part  in  aviation  contests  in  this  country 
it  was  agreed  that  the  Aero  Club  of  America,  as  the 
American  representative  of  the  International  Aeronautic 
Federation,  should  approve  only  such  public  contests 
as  may  be  licensed  by  the  Wright  Company  and  that 
the  Wright  Company,  on  the  other  hand,  should  en- 
courage the  holding  of  open  meets  or  contests  where- 
ever  approved  as  aforesaid  by  the  Aero  Club  of  America 
by  granting  licenses  to  promoters  who  make  satisfactory 
arrangements  with  the  company  for  its  compensation 
for  the  use  of  its  patents.  At  such  licensed  meet  any 
machine  of  any  make  may  participate  freely  without 
securing  any  further  license  or  permit.  The  details  and 
terms  of  all  meets  will  be  arranged  by  the  committee 
having  in  charge  the  interests  of  both  organizations. 


CHAPTER  XXIV. 

HINTS  ON  PROPELLER  CONSTRUCTION. 

Every  professional  aviator  has  his  own  ideas  as  to  the 
design  of  the  propeller,  one  of  the  most  important  fea- 
tures of  flying-machine  construction.  While  in  many 
instances  the  propeller,  at  a  casual  glance,  may  appear 
to  be  identical,  close  inspection  will  develop  the  fact  that 
in  nearly  every  case  some  individual  idea  of  the  designer 
has  been  incorporated.  Thus,  two  propellers  of  the  two- 
bladed  variety,  while  of  the  same  general  size  as  to 
length  and  width  of  blade,  will  vary  greatly  as  to  pitch 
and  "twist"  or  curvature. 

What  the   Designers   Seek. 

Every  designer  is  seeking  for  the  same  result — the 
securing  of  the  greatest  possible  thrust,  or  air  displace- 
ment, with  the  least  possible  energy. 

The  angles  of  any  screw  propeller  blade  having  a 
uniform  or  true  pitch  change  gradually  for  every  in- 
creased diameter.  In  order  to  give  a  reasonably  clear 
explanation,  it  will  be  well  to  review  in  a  primary  way 
some  of  the  definitions  or  terms  used  in  connection  with 
and  applied  to  screw  propellers. 

Terms  in  General  Use. 

Pitch. — The  term  "pitch,"  as  applied  to  a  screw  pro- 
peller, is  the  theoretical  distance  through  which  it  would 
travel  without  slip  in  one  revolution,  and  as  applied  to 
a  propeller  blade  it  is  the  angle  at  which  the  blades  are 
set  so  as  to  enable  them  to  travel  in  a  spiral  path  through 

213 


214  FLYING   MACHINES: 

a  fixed  distance  theoretically  without  slip  in  one  revolu- 
tion. 

Pitch  speed. — The  term  "pitch  speed"  of  a  screw  pro- 
peller is  the  speed  in  feet  multiplied  by  the  number  of 
revolutions  it  is  caused  to  make  in  one  minute  of  time. 
If  a  screw  propeller  is  revolved  600  times  per  minute, 
and  if  its  pitch  is  7  ft.,  then  the  pitch  speed  of  such  a 
propeller  would  be  7x600  revolutions,  or  4200  ft.  per 
minute. 

Uniform  pitch. — A  true  pitch  screw  propeller  is  one 
having  its  blades  formed  in  such  a  manner  as  to  enable 
all  of  its  useful  portions,  from  the  portion  nearest  the 
hub  to  its  outer  portion,  to  travel  at  a  uniform  pitch 
speed.  Or,  in  other  words,  the  pitch  is  uniform  when  the 
projected  area  of  the  blade  is  parallel  along  its  full 
length  and  at  the  same  time  representing  a  true  sector 
of  a  circle. 

All  screw  propellers  having  a  pitch  equal  to  their 
diameters  have  the  same  angle  for  their  blades  at  their 
largest  diameter. 

When  Pitch  Is  Not  Uniform. 

A  screw  propeller  not  having  a  uniform  pitch,  but 
having  the  same  angle  for  all  portions  of  its  blades,  or 
some  arbitrary  angle  not  a  true  pitch,  is  distinguished 
from  one  having  a  true  pitch  in  the  variation  of  the  pitch 
speeds  that  the  various  portions  of  its  blades  are  forced 
to  travel  through  while  traveling  at  its  maximum  pitch 
speed. 

On  this  subject  Mr.  R.  W.  Jamieson  says  in  Aeronau- 
tics: 

"Take  for  example  an  8-foot  screw  propeller  having  an 
8-foot  pitch  at  its  largest  diameter.  If  the  angle  is  the 
same  throughout  its  entire  blade  length,  then  all  the  por- 
ions  of  its  blades  approaching  the  hub  from  its  outer  por- 


CONSTRUCTION   AND    OPERATION  215 

tion  would  have  a  gradually  decreasing  pitch.  The  2-foot 
portion  would  have  a  2-foot  pitch ;  the  3-foot  portion  a  3- 
foot  pitch,  and  so  on  to  the  8-foot  portion  which  would 
have  an  8-foot  pitch.  When  this  form  of  propeller  is 
caused  to  revolve,  say  500  r.p.m.,  the  8-foot  portion  would 
have  a  calculated  pitch  speed  of  8  feet  by  500  revolutions, 
or  4,000  feet  per  min. ;  while  the  2-foot  portion  would 
have  a  calculated  pitch  speed  of  500  revolutions  by  2  feet, 
or  1,000  feet  per  minute. 

Effect  of  Non-Uniformity. 

"Now,  as  all  of  the  portions  of  this  type  of  screw  pro- 
peller must  travel  at  some  pitch  speed,  which  must  have 
for  its  maximum  a  pitch  speed  in  feet  below  the  calcu- 
lated pitch  speed  of  the  largest  diameter,  it  follows  that 
some  portions  of  its  blades  would  perform  useful  work 
while  the  action  of  the  other  portions  would  be  negative 
— resisting  the  forward  motion  of  the  portions  having  a 
greater  pitch  speed.  The  portions  having  a  pitch  speed 
below  that  at  which  the  screw  is  traveling  cease  to  per- 
form useful  work  after  their  pitch  speed  has  been  ex- 
ceeded by  the  portions  having  a  larger  diameter  and  a 
greater  pitch  speed. 

"We  might  compare  the  larger  and  smaller  diameter 
portions  of  this  form  of  screw  propeller,  to  two  power- 
driven  vessels  connected  with  a  line,  one  capable  of  trav- 
eling 20  miles  per  hour,  the  other  10  miles  per  hour.  It 
can  be  readily  understood  that  the  boat  capable  of  trav- 
eling 10  miles  per  hour  would  have  no  useful  effect  to 
help  the  one  traveling  20  miles  per  hour,  as  its  action 
would  be  such  as  to  impose  a  dead  load  upon  the  latter's 
progress." 

The  term  "slip,"  as  applied  to  a  screw  propeller,  is  the 
distance  between  its  calculated  pitch  speed  and  the  actual 


216  FLYING   MACHINES: 

distance  it  travels  through  under  load,  depending  upon 
the  efficiency  and  proportion  of  its  blades  and  the  amount 
of  load  it  has  to  carry. 

The  action  of  a  screw  propeller  while  performing  use- 
ful work  might  be  compared  to  a  nut  traveling  on  a 
threaded  bolt ;  little  resistance  is  offered  to  its  forward 
motion  while  it  spins  freely  without  load,  but  give  it  a 
load  to  carry ;  then  it  will  take  more  power  to  keep  up  its 
speed ;  if  too  great  a  load  is  applied  the  thread  will  strip, 
and  so  it  is  with  a  screw  propeller  gliding  spirally  on  the 
air.  A  propeller  traveling  without  load  on  to  new  air 
might  be  compared  to  the  nut  traveling  freely  on  the  bolt. 
It  would  consume  but  little  power  and  it  would  travel  at 
nearly  its  calculated  pitch  speed,  but  give  it  wrork  to  do 
and  then  it  will  take  power  to  drive  it. 

There  is  a  reaction  caused  from  the  propeller  projecting 
air  backward  when  it  slips,  which,  together  with  the  sup- 
porting effect  of  the  blades,  combine  to  produce  useful 
work  or  pull  on  the  object  to  be  carried. 

A  screw  propeller  working  under  load  approaches  more 
closely  to  its  maximum  efficiency  as  it  carries  its  load 
with  a  minimum  amount  of  slip,  or  nearing  its  calculated 
pitch  speed. 

Why  Blades  Are  Curved. 

It  has  been  pointed  out  by  experiment  that  certain 
forms  of  curved  surfaces  as  applied  to  aeroplanes  will  lift 
more  per  horse  power,  per  unit  of  square  foot,  while  on 
the  other  hand  it  has  been  shown  that  a  flat  surface  will 
lift  more  per  horse  power,  but  requires  more  area  of  sur- 
face to  do  it. 

As  a  true  pitch  screw  propeller  is  virtually  a  rotating 
aeroplane,  a  curved  surface  may  be  advantageously  em- 
ployed when  the  limit  of  size  prevents  using  large  plane 
surfaces  for  the  blades. 

Care  should  be  exercised  in  keeping  the  chord  of  any 


CONSTRUCTION  AND   OPERATION  217 

curve  to  be  used  for  the  blades  at  the  proper  pitch  angle, 
and  in  all  cases  propeller  blades  should  be  made  rigid  so 
as  to  preserve  the  true  angle  and  not  be  distorted  by 
centrifugal  force  or  from  any  other  cause,  as  flexibility 
will  seriously  affect  their  pitch  speed  and  otherwise  affect 
their  efficiency. 

How  to  Determine  Angle. 

To  find  the  angle  for  the  proper  pitch  at  any  point  in 
the  diameter  of  a  propeller,  determine  the  circumference 
by  multiplying  the  diameter  by  3.1416,  which  represent 
by  drawing  a  line  to  scale  in  feet.  At  the  end  of  this  line 
draw  another  line  to  represent  the  desired  pitch  in  feet. 
Then  draw  a  line  from  the  point  representing  the  desired 
pitch  in  feet  to  the  beginning  of  the  circumference  line. 
For  example: 

If  the  propeller  to  be  laid  out  is  J  feet  in  diameter,  and 
is  to  have  a  7-foot  pitch,  the  circumference  will  be  21.99 
feet.  Draw  a  diagram  representing  the  circumference 
line  and  pitch  in  feet.  If  this  diagram  is  wrapped  around 
a  cylinder  the  angle  line  will  represent  a  true  thread  7 
feet  in  diameter  and  7  feet  long,  and  the  angle  of  the 
thread  will  be  17^4  degrees. 

Relation  of  Diameter  to   Circumference. 

Since  the  areas  of  circles  decrease  as  the  diameter 
lessens,  it  follows  that  if  a  propeller  is  to  travel  at  a  uni- 
form pitch  speed,  the  volume  of  its  blade  displacement 
should  decrease  as  its  diameter  becomes  less,  so  as  to 
occupy  a  corresponding  relation  to  the  circumferences  of 
larger  diameters,  and  at  the  same  time  the  projected 
area  of  the  blade  must  be  parallel  along  its  full  length 
and  should  represent  a  true  sector  of  a  circle. 

Let  us  suppose  a  7-foot  circle  to  be  divided  into  20 
sectors,  one  of  which  represents  a  propeller  blade.  If  the 
pitch  is  to  be  7  feet,  then  the  greatest  depth  of  the  angle 


218  FLYING   MACHINES: 

would  be  1/20  part  of  the  pitch,  or  4  2/10  inch.  If  the 
line  representing  the  greatest  depth  of  the  angle  is  kept 
the  same  width  as  it  approaches  the  hub,  the  pitch  will 
be  uniform.  If  the  blade  is  set  at  an  angle  so  its  pro- 
jected area  is  1/20  part  of  the  pitch,  and  if  it  is  moved 
through  20  divisions  for  one  revolution,  it  would  have  a 
travel  of  7  feet. 


CHAPTER  XXV. 

GLOSSARY   OF   AERONAUTICAL  TERMS. 

Aerodrome. — Literally   a   machine  that  runs  in  the  air. 

Aerofoil. — The  advancing  transverse  section  of  an  aero- 
plane. 

Aeroplane. — A  flying  machine  of  the  glider  pattern, 
used  in  centra-distinction  to  a  dirigible  balloon. 

Aeronaut. — A  person  who  travels  in  the  air. 

Aerostat. — A  machine  sustaining  weight  in  the  air.  A 
balloon  is  an  aerostat. 

Aerostatic. — Pertaining  to  suspension  in  the  air ;  the 
art  of  aerial  navigation. 

Ailerons. — Small  stabilizing  planes  attached  to  the  main 
planes  to  assist  in  preserving  equilibrium. 

Angle  of  Incidence. — Angle  formed  by  making  compar- 
ison with  a  perpendicular  line  or  body. 

Angle  of  Inclination. — Angle  at  which  a  flying  machine 
rises.  This  angle,  like  that  of  incidence,  is  obtained 
by  comparison  with  an  upright,  or  perpendicular  line. 

Auxiliary    Planes. — Minor  plane   surfaces,   used   in   con- 
•  junction  with  the  main  planes  for  stabilizing  purposes. 

Biplane. — A  flying-machine  of  the  glider  type  with  two 
surface  planes. 

Blade  Twist. — The  angle  of  twist  or  curvature  on  a 
propeller  blade. 

Cambered. — Curve  or  arch  in  plane,  or  wing  from  port 
to  starboard. 

Chassis. — The  under  framework  of  a  flying  machine ;  the 
framework  of  the  lower  plane. 

219 


220  FLYING   MACHINES: 

Control. — System  by  which  the  rudders  and  stabilizing 
planes  are  manipulated. 

Dihedral. — Having  two  sides  and  set  at  an  angle,  like 
dihedral  planes,  or  dihedral  propeller  blades. 

Dirigible. — Obedient  to  a  rudder;  something  that  may 
be  steered  or  directed. 

Helicopter. — Flying  machine  the  lifting  power  of  which 
is  furnished  by  vertical  propellers. 

Lateral  Curvature. — Parabolic  form  in  a  transverse  di- 
rection. 

Lateral  Equilibrium  or  Stability. — Maintenance  of  the 
machine  on  an  even  keel  transversely.  If  the  lateral 
equilibrium  is  perfect  the  extreme  ends  of  the  ma- 
chine will  be  on  a  dead  level. 

Longitudinal  Equilibrium  or  Stability. — Maintenance  of 
the  machine  on  an  even  keel  from  front  to  rear. 

Monoplane. — Flying  machine  with  one  supporting,  or 
surface  plane. 

Multiplane. — Flying  machine  with  more  than  three  sur- 
face planes. 

Ornithopter. — Flying  machine  with  movable  bird-like 
wings. 

ParaboHc  Curves. — Having  the  form  of  a  parabola — a 
conic  section. 

Pitch  of  Propeller  Blade.— See  "Twist." 

Ribs. — The  pieces  over  which  the  cloth  covering  is 
stretched. 

Spread. — The  distance  from  end  to  end  of  the  main  sur- 
face ;  the  transverse  dimension. 

Stanchions. — Upright  pieces  connecting  the  upper  and 
lower  frames. 

Struts. — The  pieces  which  hold  together  longitudinally 
the  main  frame  beams. 

Superposed. — Placed  one  over  another. 


CONSTRUCTION   AND    OPERATION  221 

Surface  Area. — The  amount  of  cloth-covered  supporting 
surface  which  furnishes  the  sustaining  quality. 

Sustentation. — Suspension  in  the  air.  Power  of  sus- 
tentation  ;  the  quality  of  sustaining  a  weight  in  the  air. 

Triplane. — Flying  machine  with  three  surface  planes. 

Thrust  of  Propeller. — Power  with  which  the  blades  dis- 
place the  air. 

Width. — The  distance  from  the  front  to  the  rear  edge 
of  a  flying  machine. 

Wind  Pressure. — The  force  exerted  by  the  wind  when 
a  body  is  moving  against  it.  There  is  always  more 
or  less  wind  pressure,  even  in  a  calm. 

Wing  Tips. — The  extreme  ends  of  the  main  surface 
planes.  Sometimes  these  are  movable  parts  of  the 
main  planes,  and  sometimes  separate  auxiliary  planes. 


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